2002 Hyundai Accent gear oil

[Clement]

RedLine MTL

That's all you need to know. As smooth as can be.

 

[Clement]

I'll tag an observation/question on to this.

My car's specs call for a 75w-90 gear oil, special Hyundai stuff. Local dealerships wouldn't sell it to me. I went and bought Redline MT90. Notchy notchy notchy! I saw about the MTL/MT90 blends, so I went and did that. Better, but still notchy when cold. It was most noticeable when I was leaving work. I exit my work parking lot onto a 45 mile/hr road, about 1.5 miles later I have to slow down/stop in a left turn lane to get onto a highway. Downshifting on the cold tranny was still notchy, and then accelerating on the entrance ramp was sometimes notchy.

I recently just switched to 100% MTL (70w-80) and it shifts great! Smooth as can be! The old fluid was still reddish and clean looking when it drained out, about 1.5 years on it.

Why would a lower viscosity than recommended fluid work better than the recommended fluid? Would Hyundai expect the recommended fluid to shear down to a thinner fluid? Does Redline just have a high film thickness/strength that allows the use of a thinner fluid?

I'm curious about this.

 

[FazerZ]

The lower viscosity fluid is going to reduce shifting effort. A lot of the OE designs are moving to friction-lined synchronizers that benefit from lower viscosity, friction modified fluids, hence the movement to ATF for fills. However, wear protection from ATF is not so great and therefore requires increased service intervals for long life (even if the OEM recommends no service or sparse service intervals).

It sounds like the MT90 was way too thick even after warmup. This is a small transaxle w/ very light duty torque requirements. I would imagine ATF or 10W-30 motor oil, or a special formulation like Redline MTL, or SPF MTF-P would work great (as you found).

It's probably likely the original factory fill was just ATF, even if the owner's manual spec's out a different fluid.

Did the original fill shift well?

DH

 

[Ray H]

Hyundai's MTF is a Group III synthetic gear oil rated GL-4.

 

[goodvibes]

I'd try to find a heavier oil that worked for you. Maybe SF when they're back or GM grape juice which isn't bad at all. The 50/50 mix is on the low side of 90w so it's still OK but the 80w may not offer enough film strength to protect a transaxle designed for 90w when warm.