Anyone use Amsoil in their Manual Transmission?

Just curious. I have a 1990 Montero (4-wheel drive with a manual transmission) and Mitsubishi specifies a GL4 75w-85w oil and the Amsoil fits that spec. Also, Mitsubishi recommends to add their Friction Modifier to the transmission. What does the Friction Modifier actually do, and is it necessary when using the Amsoil product? Thanks.

Reply to
Buffalo
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Most people find that Penzoil Syncromesh is the prefered lube for their gear box.

I run a $4,000 custom modified Mitsu 5 speed and the specialist that builds the box recommends Penzoil.

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's cheap and works great. This is the SAME product GM repackages and sells as Syncroshift for more money.Friction modifiers are additive packages that increase the friction of the oil to help out gear syncros. You really do need some type of friction modifier but most manual trans lubes already contain it.

Reply to
simpleton

Actually, friction modifiers are designed for use in limited slip differentials.

Synchros are designed to work without additives, although friction modifiers can certainly affect them. If you have any details or recommendations about using LS modifiers to tweak synchro performance, I'm all ears.

IME, the GL-5 or GL-4/GL-5 oils don't work well in many manual trannys since they are too slick for proper synchro action, and in the case of cheap oils, they attack the synchro material and wear them more quickly. Using a proper GL-4 is the best answer, and Amsoil does have one true GL-4 in their offering. I use it and it's fine. Another true GL-4 is Redline MT-90.

Dave

Reply to
David Geesaman

David the syncros in Mitsubishi transmissions definately are designed for use with friction modifers. The two most popular manual transmission lubes Penzoil Syncromesh and BG Syncroshift both contain friction modifiers. Mitsubishi also sells a friction modifier additive package for use in their transmissions.

The reason GL-5 lubes are not used in manual gearboxes is not because they are any more slippery than GL-4 or cheap but because the additives in the EP (extreme pressure) package attack brass and bronze. I am unaware of any GL-5+ lube that is "yellow metal friendly". They all stink of sulphur too....

The top Mitsu transmission specialists in the U.S. agree.

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" For most transmissions we recommend Pennzoil Synchromesh. For drag use or high horsepower cars please contact us."
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Reply to
simpleton

Thanks for the reply. Mitsubishi does recommend a Friction Modifier for the manual trans in my 1990 Montero (4wd). BTW, have you tried the Pennzoil Synchromesh? I installed the Amsoil MTG 75w-90w gear oil and I will now add the Friction Modifier from Amsoil (they recommended it) and see what happens. If I had to do it all over again, I probably would have used the Pennzoil Synchromesh gear oil, even though it is not API or GL rated. It is friendly to yellow metals and does contain Friction Modifiers.

Reply to
Buffalo

Thanks for your informative replies. I did install the Amsoil MTG (75w-90w GL-4) gear oil and now I will add their (Amsoil) Friction Modifier to it. I seem to get a grind going into second and sometimes when downshifting into 3rd after the tranny gets hot. Next time, however, I will use the Pennziol Synchromesh as you recommend.

Reply to
Buffalo

Thanks for the extra info. I was not aware of the specialty of the mitsu synchros. I have to wonder if the Mitsu specified LS additive simply offsets the super low friction to make the common GL-5 more like a GL-4.

FYI, there are indeed GL-5s that are yellow metal friendly, since there are many ways to make an add pack that meet GL-5 requirements. The issue is that it takes more technology and cost to do it without attacking yellow metals, so many of them aren't set up that way. Royal Purple is one such GL-5. As well, racing gear oils are designed specifically for dog boxes, so the add packs are loaded to the extreme. Some people mistakenly use racing gear oils in their synchro trannys.

Dave

Reply to
David Geesaman

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