From: Arvid Jedlicka Date: Wed, 07 Feb 1996 16:31:34 -0600 Subject: RedLine Oil, my results I called Redline today and asked to speak with an engineer. A fellow named Tim quickly returned the call and we discussed MTL-90, 75w-90NS, 75w-90, and 75w-140NS at length. The definitive answer to the question 'What do I put in my '91-'95 MR2 Turbo transmission/differential?' is: (drum roll please) - It depends. And I fully agree with that answer. (insert the standard disclaimer about taking absolutely no responsibility for anything here) Our discussion: Toyota (not just MR2) transmission/differential assemblies are, in general, a "difficult" problem for them. They get many calls from individuals hoping to improve shifting, which implies that "less than great shifting" is the nature of the beast. He has many cases where the results were reported as satisfactory, but also has cases where the results were not as good. Because the limited-slip unit is viscous-coupled, the additives in their 'limited-slip' lubricants (i.e. without the 'NS' suffix) serves no purpose. The disclaimer on the limited-slip lubricants container is directed at older cars, newer vehicles having no parts that are affected by the minimal amount of active sulfites in the lube. As is the norm, trade-offs were made in each of the products, and we spoke in generalities. My(your) specific car and my(your) specific use may result in different experiences. MTL-90 is the "sticky-est" of the lubes we discussed, which is good for synchronizers and therefore shifting. However, it also has the lowest EP rating (I think it's only GL-4), and therefore is does not handle stress loads as well, which is bad for gears and bearings. 75w-90NS and 75w-90 are similar. Both are less "sticky" than MTL-90, but have higher EP ratings (GL-5 I believe). 75w-90 has the (in our case useless but not harmful) limited slip additive, and therefore is slightly less "sticky" than the 75w-90NS. However 75w-90 has a slightly higher load value (not enough to raise if out of the GL-5 category, but enough to differentiate it from 75w-90NS). Therefore 75w-90 will handle higher loads, but not shift as well as 75w-90NS. (see note on good, bad, etc..) 75w-140NS has a higher load rating than either of the 75w-90's. (again not enough to raise if out of the GL-5 category, but enough to differentiate it from the 75w-90'S). A side effect of the higher weight is that the "stickiness" is closer to the MTL-90 than the 75w-90's. MTL-90, 75w-90NS and 75w-90, because of the lighter weight compared to the 75w-140NS, are better heat transfer agents, allowing heat from the interior of the assembly to be moved to the exterior and dissipated. Therefore the 75w-140NS trade-off is the better shifting compared to 75w-90NS and 75w-90 and the highest load factors against the better cooling ability of MTL-90, 75w-90NS and 75w-90. Good, bad, better, worse, are all relative to the lubes we discussed. Tim felt that their lubes were good enough that even a "bad" match (because it is only GL-4, compared to the GL-5 suggested in the owners manual) such as MTL-90 would not present a real problem in everyday use (i.e. the user's actions was based upon a conscientious decision to have good shifting at the expense of not being able to go endurance racing or tow the boat and trailer to the lake.). RedLine recommends 75w-90 for the '91-'95 MR2 Turbo application. Personally, I have tried the original Toyota gear lube, Valvoline 75w-90 organic, Valvoline 75w-90 synthetic, and RedLine 75w-140NS. I live in Minnesota where the normal summer temperature is 40-60 in the morning and 60-80 in the afternoon. My reaction to the different lubes are: None of them shift well when the car is cold. The Valvoline synthetic and RedLine shift well as the car warms up (5-15 minutes into the drive). The Toyota and Valvoline organic does not shift well during this period. The RedLine shifts well after the car is hot (20 minutes plus into the drive) and while autocrossing, the Toyota and Valvolines do not. I am therefore quite happy with the 75w-140NS that I am currently using, and will be using 75w-140NS when I do the spring-time "replace all the fluids because the car has been sitting all winter" ritual. It should be noted that I am not overly concerned about heat disipation because my high performance work is autocrossing and, after all, Minnesota and "overheating" is an oxymoron. Hopefully this has been educational and helpful. Comments welcome, Arvid P.S. I faxed Tim a copy of this e-mail and he had no problem with it being placed on the net.
From: "Burns, James B." (BurnsJB1@central.ssd.jhuapl.edu) Date: Wed, 11 Sep 1996 09:37:00 -0400 Subject: MR2 Re: MKII Tranny Oils I don't think there is a "correct" answer for which is the right Red Line gear oil for the MKII Turbo, but here is some info to help you decide for yourself. Calling Red Line directly was no help because they gave 5 different answers during one 20 minute phone call, and different answers again the next time I called. For my '91T the shop manual calls for 75W-90 GL-5. For my '94T the manual calls for 75W-90 GL-3 and says that GL-4 or GL-5 may be used if GL-3 is not available. It seems strange that they would require less protection in the newer cars so maybe they found that the GL-3 or 4 shifts better than GL-5. John Broderick of Mr.2PP said that he talked to a Red Line engineer and the engineer said that GL-4 shifts better than GL-5. Red Line MTL is 75W-80 GL-4. Red Line MT-90 is 75W-90 GL-4. The Red Line brochure has the exact same words for both (proper friction coefficient for synchros, improved synchro protection, etc.). I think MT-90 may be the best choice since it meets Toyota's spec of 75W-90 weight oil. However, according to John B. the MTL offers better shifting than the MT-90. Red Line's 75W-90 and 75W-90NS are GL-5 rated. I initially put 75W-90 in my '94T with LSD, but noticed that the bottle said "not for use with copper synchros". The 75W-90NS said "improved protection for synchros" so I switched to the 75W-90NS. The Silly Putty LSD doesn't need the friction modifiers in the 75W-90 anyway. So I'm on my 3rd gear oil change in less than 10K miles. I will probably try the MT-90 at the next change to see if it improves shifting. This will still meet Toyota's spec for the '94T which is important since this car is still under warranty. The weak part of the Turbo trannies (especially '91-92) appears to be the synchros. I have seen many with bad synchros but have never heard of the gears or bearings failing. I think that MTL or MT-90 may offer the best protection for the synchros by getting them to engage properly. This may make them the best choice for the MR2T since the GL-5 gear protection is not as important as saving the synchros. I just put MTL in my '91T which will see heavy track use and fast high-rpm shifts, hoping to keep the synchros from dying. If my tranny blows up I'll switch to something else (and install a Quaife LSD :-)). As far as the Red Line MTL saying "not for use in RWD cars", this means rear differentials, not transaxles. Both my '91T and '94T shift very nicely so I don't expect to see much improvement in shifting regardless of which oil I use. I know the '91s are known for notchy shifting but mine is very smooth and easy and has only used the stock Toyota lube until now. The '94 shifting is more like a toggle switch -- shorter throw but a little higher effort. Hope this helps. Brad Burns