firechicken_3

iTrader: (4)

ok i know this has been beat to death, but i hear conflicting stories on what to use...........

book says ATF
rb83l69 says to use gear oil 75w-90

my thought is since i am in eastern iowa, and the car does get driven occasionally when its cold. so how about using, a motor oil like 10w-30, or 15w-40

any thoughts??????????????

SLOW5.0

Look at the Trans. It should have a sticker on it. Mine said to use Dextron. I used Dextron. If its a WC T-5 something about the Sync that needs friction so using Motor Oil would not be good. Guess it all depends on what year trans, some took gear oil, some took motor oil, and some took tranny fluid.

RB83L69

GM flip-flopped back and forth a couple of times on their fluid spec, without there being any change whatsoever in the actual transmission (which they didn't actually manufacture anyway). No parts were changed in between their fluid recommendation changes.

All of the 1st design transmissions have identical bearings, shafts, synchros, etc. There is no difference among them that calls for different lube requirements. Similarly, all of the 2nd design ones have all the same parts, and therefore all have the same lube needs. Some people have said that gear lube is bad for the composition clutches in the 2nd design; I have never seen evidence of this.

Regardless of how confised GM was on this matter, the parts themselves determine what the right fluid is. I of course have no way of knowing why they decided what they did; but I suspect that due to CAFE, they tried to use the ATF wherever possible, and discovered that it led to warranty problems in the earlier boxes, which is why they switched back to gear lube.

Either fluid will work in either trans as far as I can tell. Synthetic gear lube is probably the best choice all araound. I run half Mobil 1 gear lube and half Mobil 1 ATF in my 2nd design T-5; its previous owner ran Red Line MTL in it; it seems to work just fine after many, many miles like this. The 1st design transmissions were installed in lots of different cars made all over the world; some of the auto companies called for gear lube, some for ATF, again with no difference whatsoever in any of the actual internal parts.

Now I'm no genius, nor do I claim to have superior knowledge of any kind; but I've taken apart a bunch of these transmissions, and my comments are based on what I see inside of them, not on reading some magazine or something, or on what "I've heard", or any of that. Just what's in the transmissions.

I'd like to know what if anything B-W recommends, considering the lack of consistency and the confusion world-wide among the car mfrs that bought and installed their product.

ede

i'm running amsoil synthetic gear oil in my 90 chevy 4x4, switched it to that after i bought it few years ago. it had atf in it. no problems yet