Oil

[kyle4501]

I guess it may be semantics, but to me there is a difference between 'fine' & 'will work if its all that's available' & 'its better than nothing'.

Of course, any oil is better than no oil, but if someone asks what should be used, I still think the manufacturers specification is where one should start & deviate from there when special circumstances require it.

I know there are exceptions to every rule. However, I think it is important to explain the reasons why a deviation from the manufacturer's specification is acceptable or needed.
Clifford brought up a good point about the 71 series using oil to cool of the piston. Things like that make a difference, may be a small one, but still. . . .

A fleet may choose to run something else due to a host of reasons that don't apply to my use, that is why I want more details.

I have several friends that thought their 8V71 needed rebuilding due to oil consumption & smoking issues - the fix was replacing the 15w40 with the correct 40wt - no more noticeable smoke & oil consumption dropped considerably.

[Eagle]

Welcome back Geoff get ready the next thing coming at you will be the BS from Charlies Tejas web site LOL

good luck

I also would like to welcome you back we need you 2 stroke mechanics on here.

JCB

[jaypullen]

So does anyone have any ideas on getting more power out of my 6v71, hills kill me I have a blower but no turbo any help Thanks JPULLEN

[JohnEd]

I think I am getting my fingers wrapped around this issue.  Always a bad sign when I see a light at the end of the tunnel....cataracts.

As Kyle said: "40W stopped the excessive oil consumption" and leaks no doubt and dissuaded some from having their engines overhauled.  That's za big plus!!!!!

From day one I have heard all (at least I thought all) recommend against any multi-grade in a two stroke.  The point I pondered was who else makes a 2 stroke besides DD and why is there oil out there that carries a cf-2, 2 stroke applications spec, approval when DD doesn't approve any multi stuff for their 2 strokes?

There  have been many, many instances where a Knut was advised to "pass" on a purchase if he found 15 W 40 in the engine and all new purchasers were advised to change oil immediately due to the mere chance that the engine was loaded with multi grade.  I have never , till now, heard any say that using the stuff was "OK" even in the slightest.  Not having total recall or infallibility I know I can be wrong.

I called the Volvo dealer up in Eugene.  He said "NEVER EVER USE SYNTHETIC in any engine with less than 60 thousand miles on it.  Hmmmmm?  So is it OK after that, I asked.  He said he thought the engine would leak excessively but there would be no damage.  He also cautioned that the DD dealer/factory authorized service in Eugene might differ and that they should have the last word.  His reasoning was that synthetic oil was so slippery and penetrated the cast iron so deeply that the rings would NEVER SEAT.  Poor compression forever?   Remember when we used NON detergent oil in a freshly rebuilt engine to allow the rings to seat?  What ever happened to that sage advice?  The last short block I bought came with the instruction to "use only high quality detergent oil".

I called the DD dealer and asked about the suitability of synthetic.  He said to definitely NOT use that stuff in a DD 2 stroke.  I asked where DD published that policy and he said "that isn't DD policy it is my own personal advice.....only mine."    Hmmmm?   "so why don't you recommend the synthetic" I asked.  His reason was that "that stuff will leak out of every gasket-ed surface on the engine".  It will make a heck of a mess.  He added that "these things have been doing just fine on Delo 40 for years so why would you want to change?"  I didn't call his attention to thew Delo 100 vs 400 issue.

In this latest discussion I noted that CF-2 rated multi grade was not specified.  Only 15W40 was called out.  I can suppose that was just an oversight.....right?

The Knut that ran that seminar in Rickreall was expert on matters oil.  As I said he told me that syn only had one drawback and that was price.  None of the 20 other Knuts attending gave the slightest hint of disagreement.  I know for a fact that the stuff has a chem affinity for iron that eclipses that of petroleum and will penetrate the iron and not give up easily.  The break-in problem makes sense to me.

So Geoff, given the respect that others I personally respect have shown you I feel it incumbent to clarify my own respect for experience and success.  That being said I would still say everything I have said on this matter and I see no contradiction.

Thank you Clifford for perspective,

John

[Iceni John]

One curious tidbit which may or may not be related to this CF2 thing.   I originally had non-CF2 40W oil in my engine when I bought it (don't ask, it's a long story), then after ABC Bus put some CF2 40W in a few weeks ago my Jake brake mysteriously started to work more-or-less properly again.   So, both oils were 40W, but one wasn't anything Detroit would want in a 6V92, and the other is kosher and copacetic  -  I'm thinking there's more to this than simple viscosity.

Any tribologists out there who can add to the prevailing confusion?   Or maybe my Jake is overly-sensitive and in touch with its inner self.

John

[Geoff]

Yup, the issue is not contracdiction-- it is availabilty of oil.  15w-40 works in a 2-stroke Detroit. 

--Geoff

[belfert]

Yup, the issue is not contracdiction-- it is availabilty of oil.  15w-40 works in a 2-stroke Detroit. 

This depends on your definition of 'works'.  No, the engine won't sieze from lack of lubrication, but you might use excessive amounts of oil and have other problems.

Mills Fleet Farm here in the Minnesota/Wisconsin area sells CF-2 40W oil for $16 for two gallons.  It is a generic brand, but it might be better than 15W-40.

[TomC]

I have seen too many test examples of comparing using straight 40 compared to 15W-40 that I always carry 12 gallons with me just in case of problems with the engine (and it has happened).

In a nut shell the difference- 15W-40 has polymers in the oil that takes a 15 weight oil act like a 40 weight oil.  4 stroke engines "relax" between power strokes giving those polymers a chance to reshape themselves.  On a 2 stroke engine, the engine essentially never relaxes-hence those polymers get squeezed down to the point that the oil is acting like a straight 15 weight oil (I'm talking about like on a hard hill pull for several minutes).  Hence during that pull, your engine will encounter very high wear compared to straight weight 40 weight. 

On our buses, the duty cycle on the engines is relatively light when compared to a big rig truck or marine use (a boat is always going up hill). So some may get away with running a 15W-40 and not have anything bad happen.  But-if you're interested in getting more then 100,000 miles out of your engine (I ran my truck engines-both a 6V-92TA and 8V-92TA 500,000 miles before overhaul), then go through the pain in the neck of locating an oil distributor that has straight 40 weight.  Right now I have 12 gallons in my bus, and 2 more 5 gal pales in my shop for next oil change.  Good Luck, TomC

[bevans6]

"In this latest discussion I noted that CF-2 rated multi grade was not specified.  Only 15W40 was called out.  I can suppose that was just an oversight.....right?"

There are no CF-2 rated multi-grade oils, so it's implied that CF-2 is straight weight.  It does come in different weights, though, I can get SAE 30, 40 and 50 locally.

Brian