I have read nothing but rave reviews about this stuff. It was also said that it lubed so very well that you could drop a sae grade and still be ok. My take was that using the called for grade in Syn would give you much better performance and it would run with less resistance AND have superior cold weather performance. At the rate that 2 strokes consume engine oil I thing that the crankcase is a bridge too far but all the other stuff would matter and affect MPG. So who is using it and where?
John
I've changed everything I own to synthetic oils except for the bus. The price for 11 gallons of synthetic oil versus the few miles I take the ole 8v71 doesn't pencil out right now. Hopefully some day I'll be able to cover a lot of miles with it and then maybe it will make more sense. Until then Rotella. Later
We put Transynd in the Allison and dropped several degrees of tranny heat. Can't tell you about MPG, but I won't run anything else in the tranny.
Just switched the differential to synthetic gear lube last week. Again, don't know if I will notice a mileage difference, but I am guessing I will never need to change the gear lube again.
I don't think you can get synthetic 40-weight that meets the DD 2-stroke specs. I would not vary from these specs one iota.
-Sean
http://OurOdyssey.BlogSpot.com
FWIW guys Royal Purple make a synthetic straight weight 40w that meets DD specs. Cole used it in 8v92 for years with great success. good luck
I am a believer in synthetic oils, for the RIGHT application and use. Several of my cars use nothing but synthetic. But when it comes to the bus, I lean toward conventional "dino" oils. First off, it is what they were designed to run on. If a DD can get 300K on a rebuild with a conventional oil, I can think of lots of ways to spend the extra coin that I would have to invest in the premium price of gallons of synthetic.
My Spicer transmission uses a conventional straight weight oil as well. Some folks have reported good results using a synthetic in this gear box. The problem is the condition of the seals. If the seals are older, the synthetics will leak much more.
Wec4104, if Detroit's were design to use the "dino" oil why does DD tell you can use the synthetic oil ,my manual dated 1988 states you can use it fwiw good luck
I guess I've read, and probably on this forum, that straight weight for the DD's unless you go to synthetic, then a multi viscosity is ok. Am I correct or is my wandering mind acting up again. Later
Some years ago I changed to synthetic Royal Purple as follows,
4104 Transmission, straight 50 weight ( or whatever was the weight that is recommended in my GM 4104 book) Made a huge difference. slide though the gears like butter.
4104/671 engine did very well.
4104 rear end, I was not sure if it would leak past the seals it did not.
Cadillac 145,000 miles did not change the oil filter soon enough, it took all the grim and dirt and dumped it in the filter, were it damaged the bearings,
Quote from: luvrbus on March 28, 2009, 07:24:39 PM
Wec4104, if Detroit's were design to use the "dino" oil why does DD tell you can use the synthetic oil ,my manual dated 1988 states you can use it fwiw good luck
I am not saying that synthetics are verboten in all DDs. I would suspect that running a synthetic in newer 4 strokes might be a completely different story. I am looking at the DD recommentations for the 6-71 and 8-71 2 strokers. My line of reasoning is as follows... If a quality straight weight oil was good for 250K-300K miles back in the 1960s, today's improved straight weight conventional oils should be good for 300K+ miles. What will a synthetic buy you beyond that?
I look at it this way... My 6-71 was in-framed 2 years ago. While I'd like to drive it more, I'm happy to hit 12K miles/year. Even using conventional oils, I will either get another two decades out of the rebuild, or something will happen beyond the control of the motor oil.
Umm, folks, "synthetic" oils are petroleum-based. So I'm not sure what the reference to "dino" oil is supposed to mean. It all comes out of the ground. FWIW.
Quote from: luvrbus on March 28, 2009, 06:34:42 PM
FWIW guys Royal Purple make a synthetic straight weight 40w that meets DD specs. Cole used it in 8v92 for years with great success. good luck
I've looked over the latest lists of oils that meet the specs, and I don't see this product.
Royal Purple does not put their specs on their web site (why not?), although marketing hyperbole is in plentiful supply.
Can you point us at a spec sheet that says this oil is even CF-2 rated?
-Sean
http://OurOdyssey.BlogSpot.com
Sean,I didn't have trouble finding the cf,cf2 ratings on the Royal Purple under the industrail division.Davenport worked for Stewart and Stevenson for 40 years and I know this guy would not use anything that would harm a 2 stroke.His 500 hp 8v92 would use 1 quart every 4500 miles this I know for a fact because he had S&S build me one and I use a quart every 4000 miles using Mobil 40w good luck
How odd!
I may have misread the document at this link, but it would appear that Royal Purple makes a Detroit Diesel lubricant.
www.ro-quip.com/Technical_Docs/Royal%20Purple/Industrial%20fluids/RP%20Motor%20Oil_ps.pdf
Hmmmm
Ha! I thought I would never see the day when our very own Sean would be wrong. :o Ha! But wait, he hasn't answered yet. ??? Oh, the suspense of it all. :P
I thought the difference between 2 cycle oil and the 4 cycle stuff was "Ash content" and some other impurities. I don't think those are in Syn so it must meet the spec....all other things being equal. Catch that disclaimer? 8) They don't add stuff to CF2 do they?
Syn is much more temp stabilized. The only reason for 40 weight over 30 is viscosity. I think. Multi grade is peewater thin when hot and I can easily see where a high clearance engine would not do well with that condition. Syn multi grade might be ok if it's viscosity, at our operating temp, is near that of 40W Dino. Also a factor is the reduced temp added by the oil circulating. Sean said his temp dropped and syn is a superior lubricant so this is where the info I got makes sense....syn runs cooler and lubes better so you can run 20w Syn where 30W dino is specified and still get adequate lube and temp protection. That isn't my lie so don't beat me up but I have heard it more than once. Seems to make sense but I will let an engineer make that call. Bush made sense at one time to me as well and I am ever more humble and soft spoken in the presence of liberals as a result. Not to wax political, now.
John
John
John
MattC,
You da man! That Royal Purple site was really interesting. Seems that 15W40 beats straight 40 wt in all regards except ash spec. Then they turn around and spec 15W40 if you are not running low sulfur fuel ORRRR the temp hits -18C. They CALL for multi grade in a two stroke. You look at those numbers and tell me what they say to you....anybody! It is so late my eyes are no longer reliable and my fingers keep hitting the wrong keys.
Matt, thank you again. And I really mean it this time,
John
Quote from: MattC on March 28, 2009, 09:46:45 PM
I may have misread the document at this link, but it would appear that Royal Purple makes a Detroit Diesel lubricant.
www.ro-quip.com/Technical_Docs/Royal%20Purple/Industrial%20fluids/RP%20Motor%20Oil_ps.pdf
Thank you, that's what I was looking for.
Quote from: JohnEd on March 28, 2009, 09:56:45 PM
Ha! I thought I would never see the day when our very own Sean would be wrong. :o Ha! But wait, he hasn't answered yet. ??? Oh, the suspense of it all. :P
John, I've been wrong many times, even on this board -- just check the archives. ;D I'm not sure, though, what you're referring to in this thread. I asked for a spec sheet, which I could not find on their web site (http://www.royalpurple.com/ (http://www.royalpurple.com/)). Which is, indeed, full of marketing hype. (OK, I just went back and looked -- I also said I "didn't
think" you could find a synthetic that met the spec.)
Quote
I thought the difference between 2 cycle oil and the 4 cycle stuff was "Ash content" and some other impurities. I don't think those are in Syn so it must meet the spec....all other things being equal. Catch that disclaimer? 8) They don't add stuff to CF2 do they?
That's not the only difference. In fact, there have been several CF-2 rated oils over the years that have not met the DD spec for sulfated ash.
And, yes, all motor oils have additives, CF-2 is no exception.
Quote
The only reason for 40 weight over 30 is viscosity. I think. Multi grade is peewater thin when hot and I can easily see where a high clearance engine would not do well with that condition. Syn multi grade might be ok if it's viscosity, at our operating temp, is near that of 40W Dino. ...
Yes, the difference between SAE 40 and 30 is viscosity, by definition.
The chief problem with lower viscosity oils in DD 2-strokes, and that includes pretty much any multi-weight, to include synthetics, is that it is nearly impossible to maintain the oil film at the bearing surfaces in the crank and rod journals. Multi-vis oils are basically made from base oil of the lower viscosity, with additives to enhance performance at the higher temperature.
DD tried, for a while, to spec 15W-40 for the 2-strokes, with poor results. If anything, a synthetic will exacerbate this problem, not help it.
Quote
Also a factor is the reduced temp added by the oil circulating. Sean said his temp dropped and syn is a superior lubricant so this is where the info I got makes sense....syn runs cooler and lubes better so you can run 20w Syn where 30W dino is specified and still get adequate lube and temp protection.
Well, maybe and maybe not. The engine is designed for the oil to run at a certain temperature, so you don't really want it to be below that design threshold.
Tribology is, of course, a science, but to me (and perhaps most of us on the board) it's a black art. I don't pretend to know even a small fraction of what tribologists deal with on a daily basis. I try to know just enough to keep my own engines out of trouble, mostly. But hey, I've dirted my DD out twice, so I don't even have a good track record with that.
What I do have at hand, though, is the DD spec, and I know I am safe (mostly) by sticking to their recommendations pretty religiously. Which is why I always ask to see the specs on any fluids going in to my engine. I'm glad to have the sheet now for another product, which is apparently esoteric enough that I have not seen it on any of the lists circulated periodically of DD 2-stroke compliant oils. It will go in my file.
That said, I'm not sure I'd spend extra on synthetic for my 8V92, given how much oil it goes through and the fact that bearings are cheap and easy to replace, whereas liner and ring wear is the real driving force behind overhaul intervals. Synthetic may help a tad here, as well, but I suspect the oil performance is far overshadowed by other factors such as combustion air and fuel quality. Remember, too, that contaminants in the oil play a major role, and it does not matter how good the oil is when you put it in -- it's still going to get contaminated in operation, one of the 2-stroke's big weaknesses. So I favor spending the money on shorter change intervals for oil and filters instead. JMO.
-Sean
http://OurOdyssey.BlogSpot.com
While I was getting my oil changed, I was thumbing through a hot rod magazine. In the ask the expert section, one asked about using synthetics. I don't remember much specifics or his sources, but this is his final line. If you bought a new car and were going to keep it the rest of you're life, yes synthetic oils would probably help you out "some". But if you are buying a used car or only plan on keeping it for a few years, there is no advantage to this expense. You are really better off to use the extra money for added total preventative maintenance. I can not argue this point as I am not an expert, just passing on what I read.
Ray D
Sean,
John, I've been wrong many times, even on this board -- just check the archives. I'm not sure, though, what you're referring to in this thread.
You must have seen my tongue pushing out my cheek in this. :P You simply must have. NOBODY is always right, I am sure. With you the wait seems to be longer than with most and you spread yourself over an unusually wide spectrum of topics. Now "accusing" someone of being always right is either a snide remark about another"s ego or a note on their consistent reliability and intellect. ??? Pick one of those! :-\ ;D ;D ;D I'm still a fan, so there! ;)
Well, maybe and maybe not.
Now there is the engineer that I just knew was lurking in there somewhere. Had to be!
The engine is designed for the oil to run at a certain temperature, so you don't really want it to be below that design threshold.
I don't think you believe that or you wouldn't be committed to Syn in your TX. They, transmissions, are designed to run best at a specific temp as well as an engine. The engine temp is controlled by the thermostat and I mention that to confirm to you that I know that. Lots of engines have oil coolers that are not thermo controlled so they just dump all the heat they can at the given ambient. My 440 engine oil runs slightly below the coolant temp till I hit 50 and then it goes slightly over. Hills take it WAY over coolant. Notice there aren't any numbers here! It is happy at 250 F and 180 F and has pushed 15K lbs down the road at 60 for the past 70 K miles and with one bearing change that it didn't need at 30 K my bearings show no wear....Amaazing. Still if the ambient drops to 32 F they want me to run a multi grade but I have never run anything but 40W and I carefully warm the engine in cold weather. But I have to agree that "they" want the engine to run within the design limits, and , again notice I have no numbers here.
Along those lines I installed a trans cooler and didn't connect it cause I knew that if I ran it cold (below 180 F) it would rob me of MPG. The first Mt. out of SD going east is Vejas Grade. Not all that bad but really long. I pulled over that first night at 10 PM to connect the cooler cause the TX hit 290 F as indicated by my "brandy knew" oil temp gauge. Ambient was 60 F so that Hayden has been on and cooling since 1990 and 50K miles and usually runs at 180 F.
DD tried, for a while, to spec 15W-40 for the 2-strokes, with poor results. If anything, a synthetic will exacerbate this problem, not help it.
I think Syns are adding new definition to oil performance. Apparently RP's 15W40 has higher viscosity at high temp than their straight 40W. ???? I don't quite understand that but then I am more easily confused than I used to be and even then it wasn't all that difficult to do.
Thank you for all your comments Sean. They all help...really.
John
Quote from: JohnEd on March 29, 2009, 10:31:47 AM
The engine is designed for the oil to run at a certain temperature, so you don't really want it to be below that design threshold.
I don't think you believe that or you wouldn't be committed to Syn in your TX. They, transmissions, are designed to run best at a specific temp as well as an engine.
Well, yes, "but." These are two very different applications. If an engineer could design a transmission that didn't heat up at all under stress, she would. A transmission is a hydraulic device, and the performance of hydraulic fluid generally only goes down as temperature goes up. Yes, there is a flip side, which is that at extremely low temperatures, the fluid might be so viscous as to increase stress on the components, but synthetic oils generally have better low-temperature characteristics as well
By contrast, engines
require heat to be efficient. If an engineer could design and engine to run hotter, he would. Generally, the higher the temperature of the combustion chamber (piston, block, liners, valves, etc.) the more complete and efficient the combustion process will be. The only reason that engines have cooling systems is that the materials they are made from will melt, distort, or break above certain temperatures. So "design" engine temperature is a compromise -- hot enough for relatively good combustion, but low enough to keep things from breaking. This is precisely why engines have thermostats -- you
want the heat to stay in the engine when it is below that design temperature, and to leave the engine when it is above.
Quote
The engine temp is controlled by the thermostat and I mention that to confirm to you that I know that. Lots of engines have oil coolers that are not thermo controlled so they just dump all the heat they can at the given ambient.
Again, yes "but."
First, engine temperature, as I am sure you know, is only coarsely controlled by the thermostat. Like many things, it is a compromise between engine complexity (and therefore cost) and performance. In a more perfect world, you would prefer to monitor the temperature of each cylinder at key points, and direct specific cooling only to the places that needed it. You'd want to turn the cooling on and off instantly. In practice, it's "good enough" to circulate coolant through the entire engine, monitor the outflow temperature of that coolant, and direct the coolant to an external heat exchanger (the radiator) as needed. Note that the coolant temperature is not nearly the same as the cylinder temperature -- the engineer has to determine the thermostat opening temperature based on how much cylinder heat ends up in the coolant versus going out the exhaust, or into the oil, or radiated directly from the block.
If one merely takes the "some cooling is good, so more is better" approach, they would be tempted to put in, say, cooler thermostats, and that would probably be a poor choice. (Increasing radiator capacity or fan speed, OTOH, provides more cooling "capacity" without messing up the engineers' design goals, because the thermostat will still keep needed heat in the engine where it belongs.)
When you look at oil coolers, if the balance of the system is such that the oil is getting hotter than it needs to be, and the coolant is having to shed excess oil heat (heat is exchanged in the block, where oil and cooling passages are close together), then an external oil cooler will help reduce the heat load on the cooling system at high engine temps. If, OTOH, the oil is already at or below optimum temperature, then an external oil cooler will do more harm than good.
This is particularly an issue with 2-stroke diesels, due to the sheer volume of oil being dumped onto the liners. Cold oil can actually reduce the temperature inside the cylinder, interfering with combustion. So, again, in a perfect world, if you had an external oil cooler, it would be bypassed until the oil was up to design temperature, whatever that is (and it is almost certainly different than the coolant design temperature).
Bear in mind that I am not saying that either synthetic oil or external oil coolers are bad for DD 2-strokes. All I am saying is that I don't know, one way or the other, because the engineering is complex and I haven't done it. Maybe somebody has, but I am always wary of marketing claims that are not backed up by solid, independent engineering.
Quote
I think Syns are adding new definition to oil performance. Apparently RP's 15W40 has higher viscosity at high temp than their straight 40W. ???? I don't quite understand that but then I am more easily confused than I used to be and even then it wasn't all that difficult to do.
Here again, I'm not a tribologist so the science behind multi-vis oils is way above my head. I just try to stick with the engine manufacturer's recommendations to be safe. In this regard, my Detroit guidance (publication 7SE270) says that only straight 40 or 50 is allowed, no multi-vis*, and for synthetic oils, "For two-stroke cycle engines, only synthetic oils which do not contain viscosity improver additives may be used."
*There is an exception for below-freezing starting conditions:
QuoteAt ambient temperatures below freezing (32° F or 0° C), sufficient starter cranking speed may not be achieved to start the engine with SAE 40 grade oils. Where starting aids are not available or at very cold temperatures (0° F to -25° F or -18° C to -32° C) even if starting aids are available, the use of multigrade SAE 15W-40 or monograde lubricant SAE 30 will improve startability. These lubricants must possess a High Temperature – High Shear Rate Viscosity (measured by ASTM D 4741 or equivalent) of 3.70 cP minimum. These oils must be replaced with monograde SAE 40 lubricants as soon as ambient conditions permit.
(emphasis theirs).
We have a "starting aid" (we can pre-heat the block with our Webasto), so we stick with the 40-weight, which is preferred in all cases once the engine is running -- it is only "startability" that is being addressed by this exception.
-Sean
http://OurOdyssey.BlogSpot.com
Quote from: Sean on March 28, 2009, 08:30:42 PM
Umm, folks, "synthetic" oils are petroleum-based. So I'm not sure what the reference to "dino" oil is supposed to mean. It all comes out of the ground. FWIW.
Dino oil is refined mineral petroleum, as opposed to synthetic, which contains compounds which are created through other processes.
Quote from: BG6 on March 29, 2009, 12:38:04 PM
Dino oil is refined mineral petroleum, as opposed to synthetic, which contains compounds which are created through other processes.
...from petroleum.
So if you believe that "normal" oil come from dinosaurs (a stereotype propagated by Sinclair, I'm pretty sure), then synthetic motor oil does, too.
There are processes to completely synthesize oil from other substances, such as the oft-touted Fischer-Tropsch process (although even then, it is not uncommon for natural gas, another "dinosaur" byproduct, to be the required methane source), but it is generally not cost-effective to produce synthetic lubricants this way. Most "synthetic" motor oils are API group III, which starts as highly refined mineral (petroleum) oil processed through hydrocracking, and/or API group IV, which are polyalphaolefins (PAO's). Note that, while PAO's are truly engineered synthetics, they are made almost exclusively from petrochemicals -- there's that dinosaur again.
BTW, I can not tell from the Ro-Quip Asia Pacific cut sheet cited earlier on Royal Purple whether this is a Group III, IV, or V synthetic.
Again, not a tribologist, yada, yada. But I have stayed in a Holiday Inn Express.
-Sean
http://OurOdyssey.BlogSpot.com