What Trans. Fluid do I use?
 

I am installing a rebuilt '74 915 in my '71 and was wondering what fluid I should use?

Swepco #201.

Nothing better for a 915 (or 901). :)

I doubt you will find any arguments with Steve's recommendation. Sweepco 201 is all I have used in my 1985 911.

Castrol is also fine. Too much faith is put in Swepco. It's just a lubricant, it can't fix a worn synchro or a mal-adjusted shift linkage.

LOL,..If you have lost as many ring & pinions as I have in 911 race cars, you might not feel the same way,.....:) :)

I've used virtually everything over the past 33+ years thats available in the US and Swepco does the best job of protecting that sensitive R&P gearset.

You are right though, no lubricant is a substitution when there are other mechanical problems at work.

Swepco 201.

I always was of the opinion that Castrol was as good as Swepco. I just never posted it until John Walker said the same thing.

I can see a particular oil making a 'slight' difference in shifting, as the additives and viscosity can affect the synchros' operation.

I can not, however, accept the argument that a specific oil is FAR superior to another NAME BRAND quality gear oil, or that Swepco will save pinion gears from impending doom, while Castrol will not.

I could be wrong. I don't think I am. But I could be.

I also use Swepco, but there are some who swear by Valvoline HD 80/140 gear lube. Any comments about this one?

Let's make this one shorter than the engine oil thread. :)

Sherwood

I'm sure that there are multuple answers to the original question but by far the bulk of the empirical evidence is w/ Swepco. My local shop owner likes Cen-Pe-Co I'm sure it's fine but don't feel like testing it when there is a well documented superior alternative.

I did test FLAPS M1 and found that I could beat the syncros w/o really trying too hard, never again.

Hi everybody. I'm a Swepco field service guy (sales). I picked up a Swepco territory here in Western KY to service the inland marine industry. You should see some of the applications 201 is used in in manufacturing, mining and transportation. it truly is some amazing stuff.

Good point about "beating the syncros hard w/out trying",....a point not often heard 'round here,..

Best,

Doyle

wm711 is Swepco a synthetic oil? I have not changed my trans oil in 8 years but would like to use something that will work as well as the synthetic oil I use for the engine (Red Line).

I just rebuilt my tranny and, knowing that the initial fill would have to be changed after 1000 km or so, I put Castrol in, rather than spending the money on Swepco. I had Swepco in there before for about 2 years (changed in myself, so I'm 100% it was swepco). I haven't noticed one lick of difference in shifting with the Castrol. Not the slightest bit. Of course, the tranny shifts much better now than it did before the rebuild, but that's because of a failed pilot bearing causing all sorts of grinding. Before that problem occurred, it shifted exactly like it shifts now.

So consider me one in the camp that Swepco isn't any better, insofar as shifting determines. Long term, I can't say, maybe there's a difference. But I don't buy the stories of "oh, I switched to swepco and it changed dramatically!". In those cases, the old tranny oil must have been REALLY old! Or maybe running very low.

Where's lubemaster to weigh in on this?

Who needs Lubemaster? I just posted the correct answer. ;)