School a Redline/Motul guy on Amsoil fluids.

[BenFenner]

Don't ask me how, but Amsoil products are pretty new to me. I've always used Redline fluids for transmissions and Motul for brake fluid. And I know these companies make great fluids across the board.
I've been doing a lot of reading, and I'm pretty sold on Amsoil for my next oil change.

What about the S52 transmission? I have some fluid in mine that can't possibly be right. The synchros aren't getting nearly enough friction to do their job and if I don't shift slowly and deliberately it can be a bit of a crunchy affair. Whatever is in there has to be much too slippery. My normal plan would be to put Redline stuff in it, but I've heard too many people say they've swapped from Redline to Amsoil and are even happier with the change.

My main question is, what Redline fluid is recommended for these transmissions? I see a lot of people say they used Redline MTL and Redline's website says that's what is popular for BMWs. But I'm more familiar with the MT-90 stuff in the Nissan FWD LSD transaxle and love it. What's the difference, and why? Maybe I just need to call Redline? The only difference I can find on the spec sheet is that the MT-90 is a bit thicker/heavier/less viscous than the MTL. Maybe that's needed for a VLSD transaxle?
Is everyone happier with Amsoil because they are using the wrong Redline fluid to begin with? Maybe Redline MT-90 would be just as nice?

Or if I'm going to go with Amsoil in the transmission, which is recommended?


And then, what should I put in the rear diff? I've got a small leak and I'm sure some worn out LSD clutches that I'm going to take care of and I'd like to see what fluid is recommended for the rear diff when I refresh that sucker.



Not trying to make this another one of "those" fluid threads. The answers I'm looking for should be simple enough, and non-polarizing (I hope). I've been doing a lot of searching, but not coming up with the answers.

[Wertles]

Amsoil MTF 5W-30 is recommended for daily driver, stock hp configurations. 75W-90 is recommended for hot climates, track cars or forced inductions applications. The M cars need Amsoil severe gear 75W-140 in the diffs. No additional additives are needed. I might have extra laying around of both. Not trying to step on anyone's toes by selling, I just ordered more than I needed and now have a few extra quarts of each.

[BenFenner]

Thanks for the info and offer Wertles. I plan a good bit ahead of time, so I'm not ready to do the transmission or diff right now (engine oil will be done soon though). So not really in the market now, but will check back later. I may also ask in general where people like to buy their Amsoil products, since I don't have anywhere local that I know of and prefer to order online.

[rf900rkw]

I have a jug of AMsoil MTL 5w/30 freshly drained... only about 10K miles on it. For sale cheap!!!

Years ago, when I went with the 5/30, I first talked to Amsoil about what to use, they said they didn't have a fluid that would work, but the 5W/30 would probably be okay. In my book, it isn't, it does exactly as you say your does. I feel it's too thick. I recently drained the Amsoil just to try a stock Dex III ATF.

MUCHO better.

Now i don't beat the crap out of the car; the ATF may not work in a track car. Certain members that do beat the piss out of their cars recommend Mobil 1 ATF. If I was going to go Redline, I would go D4 ATF. If I was to do Amsoil again, it would be equivalent ATF

[BenFenner]

These are exactly the type of responses I was hoping to get.

it does exactly as you say your does. I feel it's too thick.

Feeling too thick like the shift lever is going through molasses (until warmed up)? Or more like I described with the synchros that can't seem to keep up? Because that is usually a sign the fluid is too slippery, and that's usually the case with thinner stuff (all else being equal). But I guess it can "feel" thick to some...

[rf900rkw]

Not thick as in a gooey movement; just notchey crushey shifts. I had to shift slow to get a smooth engagement. this was a problem cold or hot. In order for the syncro to work, the oil has to be squeezed out of the contact zone of the brake ring. Thicker oil doesn't move out of the way quick enough, so the dog steps over the detent before the brake has brought the gear up/down to speed.

[BenFenner]

That's interesting. I've experienced a similar situation (at least I think) with fluid that is too slippery. The synchronizer (baulk ring) moves to the contact zone of the gear cone and slips against the gear never applying enough fiction to get the gear up to speed quick enough to allow for moderately quick and smooth engagement.
But maybe I'm wrong and that's not what was happening. I like your explanation.

[kobayashi]

A dedicated MTL that works well in our gearboxes is Royal Purple. I'm not a fan of their engine oils as there are much better options, but their Synchromax works great in applications wanting thin fluids.

For the engine, I'd go with GC, Redline 0w40 or M1 0w40.

[Scarceas]

Running the Amsoil MTF 5w30 in my gearbox and it's an improvement over what I believe was original fluid with over 160K miles on it. When I first get in the car, though, it's less than perfect. The shifting seems to return to normal within just a few minutes of driving, well before the engine oil is up to temp.

I have read that the Royal Purple is better when cold and about the same as the Amsoil when warm.

[2kredz3]

These are exactly the type of responses I was hoping to get.

Feeling too thick like the shift lever is going through molasses (until warmed up)? Or more like I described with the synchros that can't seem to keep up? Because that is usually a sign the fluid is too slippery, and that's usually the case with thinner stuff (all else being equal). But I guess it can "feel" thick to some...

The feeling you describe is much like i felt when testing redline d4atf as well as amsoil universal atf. Which i feel both are simply too thin.

The truth of the matter is anything you put in will make an improvement, depending on your driving and of course the condition of your car some fluids will work better then others.

I have provided Amsoil 5w30 manual synchromesh fluid for over 250 z3's and mz3's some do not see an improvement (typically low mileage) and the rest showed marked improvement. Twice the issue got worse (both times transmissions had mechanical damage prior to drain and fill).

Now about redline, to accomplish a simular feel to the amsoil i had to mix 1 full bottle mtl with half bottle mt90. Mtl is closer to atf so adding the mt90 made it thicker, uuc recommends using this mixture with their light weight flywheel etc. i dislike the idea of mixing, but hey if you have to use redoine then thats the way to go.

[Wertles]

I don't like the idea of mixing either but I am tempted to try one quart of MTF 75W-90 and topping off with 5W-30 after reading that article stating that their mixture would cut down on lightweight flywheel chatter which I am suffering a little bit from now. I might just go straight 75W-90 but haven't decided yet what to do. Opinions? I'm dropping the fluid in my tranny anyway because whoever rebuilt the tranny put something in there and I don't know what it is.

[2kredz3]

Just use the amsoil 75w90 mtf ;-) it will be a tad notchy when cold (first couple miles) then it will smooth out.

[BenFenner]

I'll say that I'm actually a big fan of mixing, at least within a single brand and classification of fluid. I've mixed the Redline MT-90 with the Redline Heavy Shockproof in 50/50 mix to get some of the protection of the Shockproof but avoid some of the thickness when cold of the Shockproof. 100% Shockproof was just unbearable when cold. (This is in the turbo SE-R.)

I will say for sure, if I have to choose between good cold operation and good shift feel versus transmission protection for the occasional track day, I will pick the good cold operation and shift feel. I'm already choosing a very good fluid, and the transmission I know can handle the relatively paltry stock torque output. I wouldn't be too worried about needing added protection and heat resistance.

With that said, I should be looking at the Amsoil 5w30 manual synchromesh or maybe a Redline MTL / MT-90 mix?
Am I reading things correctly?

[Bear Grylls]

I have used both the Redline 75w-90 and Amsoil 75w-90

The redline fluid performs exceptionally well when hot. Like engine at operating temp, ambient temp is above 85 and running hard. But it is pretty rough when cold.

Amsoil performs better at all operating temps in my opinion.

[kobayashi]

I have used both the Redline 75w-90 and Amsoil 75w-90

Neither one of those is the correct choice for our transmissions.

[z3papa]

I've used Amsoil products for the past three years even before our team got them as a sponsor. As part of our sponsorship, we were required to give feedback and post our assessments, all of which were very positive. Three of the guys submitted oil samples in for testing at an independent lab which found the oil was at well over 90% of original peak performance afterwards as it was when it was produced. The testing company actually asked whether new was sent in for testing,

[2kredz3]

Neither one of those is the correct choice for our transmissions.

The amsoil he is refering to is the 75w90 mtf, which is correct for these transmissions under certain conditions.

[kobayashi]

The amsoil he is refering to is the 75w90 mtf, which is correct for these transmissions under certain conditions.

BMW recommends 75w90 now?

[2kredz3]

BMW recommends 75w90 now?

Bmw recommends their fluid which does not have a weight.

But, dont get hung up on weight...a 75w90 mtf is nothing like 75w90 diff fluid.


I have done extensive testing with the various fluids and there are certain cars that i recommend the heavier fluid in for protection :-)

[kobayashi]

Again, where is the BMW recommendation for 75w90? BMW's fluid does have a weight, BTW. It's VIS40 is 58 and VIS100 is 10.6 which makes it a 70w80.

70w80 is a lot different than 75w90. Amsoil's 75w90's VIS40 is 88.4 and VIS100 is 14.8. That's not even close to what BMW recommends.

[Bear Grylls]

Again, where is the BMW recommendation for 75w90? BMW's fluid does have a weight, BTW. It's VIS40 is 58 and VIS100 is 10.6 which makes it a 70w80.

70w80 is a lot different than 75w90. Amsoil's 75w90's VIS40 is 88.4 and VIS100 is 14.8. That's not even close to what BMW recommends.

BMW also recommends we only use OEM parts and never modify our cars for performance in any way shape or form.

I have missed shifts and grinned the gear box a few times in my car and I can tell you after draining the redline fluid out, it looked brand new, was still red, and had no metal shavings.

I will run heavy weight transmission oil til the day I die in my performance cars for a reason. They get abused.

[kobayashi]

^^^ Judging your MTF based on its color is a very questionable choice. Might not get a lot of support for that one.

[Bear Grylls]

^^^ Judging your MTF based on its color is a very questionable choice. Might not get a lot of support for that one.

Your in denial

[2kredz3]

Again, where is the BMW recommendation for 75w90? BMW's fluid does have a weight, BTW. It's VIS40 is 58 and VIS100 is 10.6 which makes it a 70w80.

70w80 is a lot different than 75w90. Amsoil's 75w90's VIS40 is 88.4 and VIS100 is 14.8. That's not even close to what BMW recommends.

where to begin. . .see, this comes up every few years and I always have to go back through and explain this over and over again. I am of course well aware of the VIS #'s. Which is why I have said several times that there are certain vehicles or conditions that I recommend the thicker fluid on. For most Z3 owners the 5w30 is perfect, and just so that we have all the data here in this thread:
VIS40 is 48.3
VIS100 is 9.7

So as you can see the Amsoil most recommend actually has better flow characteristics then the OEM fluid, yet temperatures are reduced by as much as 15 degrees through better shear stability in the Amsoil products and we all know that heat is the ultimate demise of anything automotive related.

Back to the thicker fluid (75w90 MTF) It will be noticeably more notchy when cold, which is obvious when looking at the numbers. However, once warm it give the extra projection that people that have installed super chargers, live in 100+ degree climates, or run their car on the track most of the summer require to keep their car on the road. I have made it very clear to everyone on this site that I do not recommend this fluid in an average car.

Sorry in advanced if this message didn't flow, I will try to proof read it when I get home

p.s.

To me the most important thing is not that Z owners purchase Amsoil, it is that Z owners do not leave OEM fluid in longer then 30k mi. I think that BMW has lost their mind calling that fluid "lifetime". Every transmission that I have drained with OEM fluid with as little as 30k mi the fluid came out black and failed the oil analysis for wear protection. So please, just change your fluid with something! Even if it is fresh OEM fluid

[BenFenner]

Trust me when I say I know how draining these kinds of threads can be for those who've been here for a while. Also trust me when I say I tried my damndest to search for the answers (which is one reason we're only talking about transmission and diff fluids and not engine oils--I was able to find adequate oil info).
I appreciate each and every response and I'm certainly feeling more informed now than I was before. No need to go into tons of detail for me. I can search and posit with just the tiniest of info.

Thank you, and if there's more to be discussed please continue.


How about diff fluids? Recommended Redline/Amsoil daily driver solutions and track day solutions?