Spicer trans and Synthetic oils ????

[scanzel]

Has anyone used a synthetic oil in their standard trans. Does it provide any smoother shifting. What about the seals, will it cause leaking and damage the seals ? Curious minds want to know more.

[bevans6]

I use synthetic trans fluid in my spicer.  http://www.mobil.com/USA-English/Lubes/PDS/NAXXENCVLMOMobil_Delvac_Synthetic_Transmission_Fluid_50.aspx

It doesn't leak, it works fine, the tranny shifts the way it shifts, no smoother no worse.  It just is what it is.  it shifts the way it does because that's how it's designed to shift, unless it's worn out or otherwise broken.

Brian

[JohnEd]

Brian,

Great link.  Thank you for that.  It should be a Sticky and everybody that isn't using Syn should read it twice twice.  Better lube....better efficiency(MPG)...cheaper overall cost.....AND it cures Leprosy....

Thanks again,

John the believer

[Len Silva]

I don't know about the MCI, but the Spicers in the 4104 and 4106 have pressurized lubrication systems with an oil pump.  That is why they recommend the same viscosity as the engine oil.  I would be concerned that the synthetic 50-90 would be too heavy in that application.  Those transmissions do not run gear lube.

[bevans6]

The oil in the link is an SAE 50 oil, the same viscosity as any SAE50 engine oil, just optimized for transmission use.  It's not a gear oil.  Gear oil is not measured on the same viscosity index as engine type oils.  The ratings do not cross over between engine/transmission oil and gear oil.

http://www.bobistheoilguy.com/cms/index.php?option=com_content&view=article&id=48&Itemid=55

if you want interesting, 75W gear oil matches up to SAE 10 engine oil.

Brian

[JohnEd]

Len,

The viscosity of Syn is incredibly stable.  It is the all temp lube for any application...engine, trans, gear and grease.  It lubes better when hot and flows better when it is freezing and it coats all parts with a film that never gives up so it is outstanding for storage and rust prevention.

I was a believer long ago for reasons of economy/efficiency but my gun BB recently had some tech eval stuff that really opened my eyes.  They too steel strips a few inches long and hung them in a "humid box" for rust proofing eval.  The first strip was untreated, of course, and had colorful surface rust over night and was severely pitted after 14 days.  

Another strip was dipped in Bee's wax and it was rusted in a couple weeks.  Bee's wax!  Did you8 knows that that stuff was pores and wold allow water to pass through it?  Albeit slowly.  It lasted a good long whil.  

Motor oil, petro, allowed the strip to rust slowly as it receded down the strip.  The top was badly pitted and near the bottom of the strip it was barely colored.  it looked like horizontal stripes. The stuff flows down and leaves the metal completely free of protective oil in the process.  Amazing....to me.  I guess there are additives that make it cling better....in fact I am sure of it.  But, we are told that a DD doesn't like to sit for extended periods so we start the babes up and run them to op temp before laying them up for another week.  Or so I am told.  I can imagine if after a month all the oil had receded from the metal  then the seal would be starting "dry" and that would not be good.  This explained a question I had had for years which was "how in the hell could my wheel bearings be rusted on only half the surface and rust free on the other".  The RV had sat for a few years and the answer was that the dino based grease had migrated down the bearing and allowed it to rust.

I think there was a strip that had been dipped in some sort of veg oil and it did the second best.

Then they showed the result of the stay in the humid box for synthetic.  It never  rusted!  It seems that the oil penetrates into the poors of the metal and deeply and "clings" to the surface like FOREVER.  

The gist of this was that if you use petro gun oil you need to clean and re-oil your gun every six months.....as we all do with the arms we cherish.  Some of mine are over a hundred years old and one was built in 1898 and it fires into a one inch circle at 100 yards. 1 MOA, without much encouragement. 6.5 X 55!  At least once a year and that stuff is "bono fidy gun oil".  There is a new "gun oil" out there that is getting lots of attention and it is red and looks suspiciously like ATF and that stuff is syn.  I don't care if Clifford knew about this back in 06, it is news to me and maybe to some of the rest of us that are mere mortals.  This might seem a little sarcastic but it is born in respect.  The info must not be universally shared cause people keep asking.  For a truck that runs 24/7 for its useful life and is always at operational temp the record of the effectiveness of Petro is undisputed....at least by me.  If you lay your hardware up for extended periods you should consider this stuff and when you bring the babe back on line it mixes with the cheaper oil that would be suitable for a working engine.

John the slippery

By the way:  Petro is short for petroleum and Dino is short for Dinosaur derived oil.....Petro.  I spend too much time in the alt fuels BBs

[gus]

What Len says which is what the manuals say.

Read your manual and find out what is recommended, it doubt it is any different than on the GMCs although it might be.

The only advantage I can see to synthetic is it costs more and makes you feel better!!

[JohnEd]

Well there's that and they have no sulfur content with which to generate sulfuric acid dilute or migrate off the innards and leave your block and other paraphernalia with an iron oxide coating and, of course the extended oil change interval and, well it just seems to go on and on and on.  The viscosity is stable from minus 50 to 300 or some such idiocy so I don't concern myself with changing viscosity.  Most motor oil will advise you not to mix your oil brands and they don't describe an exception to that rule.  Syn recommends that you drain and fill with syn exclusively but I recall them also saying that you can add multi grade and straight Petro base motor oil without issues.  Yes, I do feel better that I am using it, and that I can afford it and the "costs more" aspect is not a plus for me. 

I'll go with the experts and all that lab analysis that says it is superior in every regard except price.  The characteristic of running at a lower temp is difficult to prove with a thermostatic controlled engine.  The differentials are a different story though.  When sys hit big, back in the day, I heard that the truckers "dove" into the diff grease product.  It was reported to lower the operating temp by 20 degrees and that adds up to less roll resistance.  Way back I read that if you switch to syn you cam drop a grade in the diff grease cause the syn is a better lube and doesn't need all the viscosity but I haven't heard that in years.  Made sense at the time and there syn grade called out was two different viscosity's.

But here again....I am not the expert on the subject.  Search for comparisons and recommendations.  And never forget that Dino oil had been in successful use for over 100 years and that doesn't, in itself prove that the claims of science on the benefit of syn are false.  If I had a leaker I would apply use the syn when laying the coach up for the winter, summer or season.  It is truly costly to spread all over the highway and common sense and frugality must prevail.

John the synthetic

[JohnEd]

I went to the Ames oil site http://www.amsoil.com/storefront/deo.aspx and in there under the heading compatibility it states without equivocation that any approved motor oil can be added to the synthetic charged crankcase and the only negative is that that charge then has the change interval of the added Dino oil.

Logically speaking, it would be foolish to market a oil that would turn to jello if you added Pennzoil by mistake or in an emergency.  I do remember one of the synthetics going so far as to say "it isn't recommended".  I think this is a non issue and the jello story is just that.

John