Gearbox Fluid, What Type Are You Using?

Generally, I believe Redline suggests MTL for non-synchro transmissions. I use Redline MT-90 in the transaxle of the Mondial ('84 QV) and it works great. Smooth shifting, warm or cold, and has held up well on the track, no degradation in performance. A friend is using the Redline 75W90 NS in his race modified 308 and loves it.

 

MTL actually is for syncro transmissions but is a GL4 instead of GL5 so Redline will not recommend it.

GL4 spec is for low to medium offset hypoid gears while GL5 is for medium to high offset hypoid gears.

The 308/328/348/355 transmissions do not have hypoid gears of any type but Ferrari specs GL5 gear oil so a lubricant supplier will not suggest any but the spec'd oil.

I am not an experimenter of that nature when it comes to client cars but I have seen 308/328 transmissions running MTL for most if not all their lives and it was the gear oil of choice for many of the 355 Challenge teams. I know of zero incidents due to it's use. That is more than enough for me.

My shop is about 20 miles down the road from Redline and I talk to them frequently. I have asked point blank about MTL and was told it would be fine but due to it's rating they cannot officially condone it's use.

I use Redline 75/90NS in the shop to keep it simple because it can be used in almost all the cars I service but when I get a shifting complaint in a 308/328/348/355 I put in MTL.

As Kris said, it comes as close to making a Ferrari shift like a Japanese car as I've seen.

 

Brian,

Thanks for the insight on MTL. Always good to learn something new. As you said, I've taken the recommendations of Redline from their website. I was planning on trying the 75W90 NS next gearbox change instead of the MT-90, but might have to give the MTL a try. The MT-90 smoothed the shifting out a lot, so would be interesting to try the MTL for comparison.

Steve

 

I just switched from Mobil 1 to Redline 75/90NS and there was a HUGE improvement, much smoother shifting and I can get the car into 2nd gear when it's cold now.

 

Nice, keep us posted on if anything changes as you accumulate miles. I had initially great results with Mobil 1, but after a few thousand miles, the gearbox started 'crunching"....switching to Redline 75/90NS fixed it for good.

 

I still like Mobil 1. Have used it since 2000. Over 114K miles and running strong.

 

Perhaps my 328 had worn synchros or something? That may be why it preferred an oil without any slip additive?

 

Dave, undoubtedly. The friction modifiers in oil for limited slip diffs aren't helpful in the gearbox. However, without the friction modifiers, the limited slip diff won't perform as intended (more slip)...although the gbox will shift easier as the syncros can match speeds easier/faster. It's really a compromise b/w the needs of ease of shifting and needs of the diff to have the right friction coeficient in the oil.

 

Hi,

....Royal Purple on my '76 GTB - shifts like butter, no diff. chatter, straight from the bottle....

Anthony

 

Hey Brian, Question on the above mentioned MTL. Do you add any friction modifier?

 

Nope, use it right out of the bottle.

 

Different animal but the Maserati Biturbos had "slow" somewhat crunchy gearboxes and any problem was completely eliminated by MTL...completely changed the character of the car and it became a pleasure to drive. That's going into my Mondial t and 355 soonest I can get to it..

Chris

 

Surprised to see nobody has mentioned NEO synthetic. Everyone I know who has tried both NEO and Redline preferred the NEO. It's has an even nicer shifting action than Redline and works just as well when it's 30 degrees outside as when it's 100.

http://www.neosyntheticoil.com/