Perhaps, these "guys" will be willing to share the cost of the transmission rebuild/repair due to seal failure, synchronizer failure (especially the ones on the main shaft) and actual gear tooth wear. "Great" is a subjective term that means nothing, unless documented...IMO. What is being compared: cost, temperature, MPG, ease in shifting-cold vs hot, MTBF (Mean Time Before Failure) lower ETs?. Maybe this is a "they said" rule.
ATF has totally different lubricating properties, and coefficient of friction level to promote long clutch friction disc life. The gear separating forces in a 4 speed transmission are totally different than those on an automatic transmission's planetary gear train as these gears are contained by the ring gear and tend to be cancelled out. Manual transmission lubricants contain an EP (Extreme Pressure) additives, a viscosity and film strength high enough to prevent actual metal to metal contact of the counter shaft and main shaft gearing during extreme loading conditions....like 1/4 mile contests. For my application, I'll continue to use a synthetic 80W-90 gear lubricant like a Mobile1 product, but to each his own....
BOB RENTON
Hello Bob, since it sounds like you're experienced/knowledgeable regarding this issue, I have additional questions.. I'm going to be servicing my A833 soon, with plans to use Sta-lube SAE 80W90 API GL-4, as recommended by Brewer's. I use Mobil 1 engine oil in my daily driver (not the car I'm asking about, here), and I'm happy with it; many trouble-free miles. So, I like Mobil 1.. you say you use Mobil 1 Synthetic 80W90. Do you like it better than Sta-lube and, if so, why? Do you use the same product in your differential? I have a bottle of Mopar Limited Slip additive (4 ounces), to add, as well, when I change the differential fluid (changing because of many years sitting idle). Thank you, Bob! If you have any other information to answer my questions, I'm all ears! I look forward to hearing from you! Thanks Again!