Synthetic lube in transaxle

[TomWesty]

I am a year round driver of my bus and it seems like my winter gigs always seem to land on sub zero nights. I usually make pretty short drives around town and my tranny is barely warm by the time I get to where I am going. Shifting a bus with standard gear lube in these temps feels like you are trying to move things through peanut butter infused with sawdust. I think I read somewhere that Bigbore had a customer who messed up their tranny by using synthetic gear lube in it, but I have also seen Gary (Aeromech) put Royal Purple in gear boxes. Just wondering if I should switch to synthetic for easier bitter cold shifting or not. Thanks for your opinions.
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[Wildthings]

For the kinds of winter temperatures you are seeing running ATF or a 0w20 or 0w30 motor oil would work. Redline also offers a 70w/75w which would be about equivalent to a 5w20. If you want a year around oil, maybe a 0w50 or 5w50. Don't think you are going to find a perfect oil for your year around use.

You might be able to find something like this in your area as well

http://www.matweb.com/search/datasheet.aspx?matguid=18456886ddec4e139f4fb040ab9ddf9b&ckck=1

[sjbartnik]

I don't know what year your Bus is so I picked this page from the '71 manual but I think it should be similar for other years too.

Here's VW's recommendations on what transmission oil to use depending on temperature. They note you can use ATF in the manual transmission at temperatures below -13 degrees F but I don't know if you're looking temps consistently that cold. You wouldn't want to do a long highway run with ATF in the trans above those kind of temps.

You might try Red Line MTL as a synthetic replacement for standard gear oil. Might help with the cold weather shifting.

EDIT: I meant to say Red Line MT-90. That's what I have a jug of. I don't know where MTL came into my head.
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[raygreenwood]

I am a big proponent of synthetic oils. I will use them whenever I can.

Synthetic gear oils...take a bit of thought an research. You need to be sure to look around at transmissions that use similar final drive angle types and synchro types....before jumping into one.

For instance:
I can tell you right now...that there is and has been a large controversy in modern manual transmissions with VW. They have changed their oil spec several times over the last few years due to some wear and damage issues.

Lots of people using the Redline MTL in several Mks of Golf and Jetta. Some have had damage issues. Most have not. Great stuff.

I mention this because the new generations of synthetic gear oils...have totally different actual consistencies....for a given rating. By this I mean...for instance...the 75/90 synthetic oils for synchromesh trans.....have the film strength and EP ratings of 75/90...but the actual viscosity and flow is similar to a cold ATF. About like a 20 weight.

While they all work....some transmissions require a thicker flowing oil regardless of advertised film strength...to make sure it gets and stays in teh right places, does not foam or aerate etc.

The hot gear oil for all weather lately has not been the Redline MTL...but the GM synchromesh (about $25 a quart).

One thing is clear though....the change interval on most of these new synthetic gear oils (at least on modern VW)...is about 35k miles....and rightfully so. It comes out looking water thin and totally brutalized. Changing the oil at 35k with the modern gear oils totally changes the shifting and sound.

Short change intervals...not lifetime fill....are the norm. Part of this is because the synthetics do not have the same anti-oxidization packages as the older hypoid oils.

Shop around and listen and look at everyone who is using a synthetic over a period of time...successfully.

Ray

[Wildthings]

I remember shrieks of terror when US manufacturers began running motor oil (and sometimes even ATF) in their manual gear boxes back in the seventies. There were lots of mechanics and owners screaming that the transmissions were going to blow up. My experience if anything was that the failure rate actually went down while the frequency of oil changes got so long that people as a group forgot that transmission oil ever needed changing. I decades ago moved my older Toyota Land Cruiser and Dodge truck over to multigrade synthetics and have never looked back, while I have also taken ACVW transaxles that would not sift well and moved them over to either ATF or something like a 5w50 motor oil. I have never had a transmission fail due to wear, but any failures have been due to some kind of high mileage breakage like a 3-4 slider or or abuse like a failed reverse gear. The transmission in my Vanagon Syncro was virtually unshiftable when I bought it at 147K miles so I played around with using both a multigrade motor oil in it and ATF in it, I eventually decided that ATF gave the best performance and put another 150K on the box before the rig was taken out of service when the engine failed.

That smoke snorting diesel truck weighing in at 40 tons that pulls out to pass you on that mountain grade has 30wt oil in his gear box, while a lot of tractors run transaxles that also function as hydraulic reservoirs that are filled with ATF.

I wouldn't fear running ATF or a multigrade motor oil in an ACVW gear box during the winter months in Oregon, let alone in Montana or Wyoming, but I am not running 150 hp and pulling a 2000# trailer up mountain grades either. YMMV

[white74westy]

I can't speak to performance of their products, specific to the cold, but I've been running the Red Line MT-90 in my rig for a few years now. I've been happy with the results...no complaints on my end.

[SGKent]

GL4 80-90 worked fine in my 1971 as low as 5F. The problem with ATF is that it won't give you the protection you need when it gets back above that -13 number. I know that in summer in Los Angeles I went to GL4 SAE 140 based on some suggestions by folks in the know and my transmission temps dropped from too hot to touch after a long drive to warm to touch. That trans lasted about 350,000 miles so that is almost double what Rick Long said to expect from an 002 before it needed a rebuild. I replaced it with an 091 and unfortunately the gearing was too much.
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[TomWesty]

Hey thanks guys! Lots to ponder...I’ll let you know what I try and how it goes.
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[aeromech]

I used Royal Purple that one time because my customer had deep pockets and that’s what he wanted to use. It was an 091 in a 1968 bus with a 2007cc engine. There were no comments either good or bad on the gear oil but the bus did run great and matched to that 091 was great at pulling hills as well as freeway driving. I’m a great mechanic no matter what Bill Fowler thinks. He’s a girly man with a hairy back. Busdaddy told me that.
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[TomWesty]

[TomWesty]

I think I’m gonna give the MT 90 a shot. I’ll report back if I remember......
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If you haven't bled on them, you haven't worked on them.
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[raygreenwood]

[rustbus]

i probably shouldnt say, cause i have no evidence of anything, but

i swapped in an unknown 091 to run with my Camper Special, and i found and filled it with synthetic. i believe it was the redline mt90, im far far away from home right now but ill be home in 2 months to verify haha

anyways, it ran nice for about 15000 km, now she howls like a banshee in all gears except 4th. not sure if its related to the synthetic vs dino oil. but my gut tells me a solid maaaybe.
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May of '72 Deluxe. 2.0L L-Jet CS & 091 trans conversion
my Bus thread

[TomWesty]

[Bleyseng]

I use Swepco 201 in all my VW's and it shifts smooth and is super quiet....yes at 15F its abit thick but warms up in a few blocks.
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87 Syncro Westy Titan Red 2.1L 2 knob 100k miles

[TomWesty]

[SGKent]

My understanding from speaking with BigBore, Erik in El Cajon, Rick Long and several others in that business is that IF the synchro rings are moly coated from the factory or rebuilder, then GL5 will cause the synchro rings to be too slippery and the trans will grind on the shifts where the moly synchro is. My 091 has 4 all moly synchro rings. Most 091 have at least 1 and up to 4 moly coated synchro rings depending what VW was using when they built your trans.

Using GL5 in a VW 091 is a crap shoot from what they have told me. The ONLY way to fix the problem if GL5 is introduced with moly synchro rings is to replace the syncho rings if they were exposed to GL5. Mike (BigBore) had one he rebuilt for someone that was only weeks old, and he told me other builders have had the same issue. It has nothing to do with a worn out trans. It does have to do with the combination of a moly coated/embedded synchro ring being too slippery when the moly absorbs GL5. Swepco 201 is a fine gear lubricant but it is GL5. If you use it and you have moly coated synchro rings you may have just bought yourself a new transmission rebuild. If you have uncoated brass synchro rings then you are Ok.

I am only passing this on because it was given to me as a warning when I rebuilt my 091 using moly coated synchro rings. The combination of GL5 and moly is so slippery that the synchros can't grab the gear cones to speed them up for the shift.

Weddle synchros. Notice the Genuine VW are Coated with Moly

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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

[SGKent]

[TomWesty]

Great info. I am currently running GL4 in what I am sure is the original 002 in my ‘71 Westy. Mileage unknown. Could be 124,000. I know my folks bought it in ‘75 and only drove it on vacation and a bit as a grocery getter. Those vacations might be several weeks long and go coast to coast and border to border though.
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If you haven't bled on them, you haven't worked on them.
Visit: www.tomcoryell.com and check out my music!