Carpokes

Since I'll be in the area changing my fuel pump, I thought I'd change the transmission fluid too. It's an LSD S-spec transmission. What's the latest and greatest on transmission fluids these days? Fairly sure I used Mobil 1 last time. Also looking at Redline and Swepco... Have any of them emerged as a clear winner in recent years?

Swepco 202, it's a synthetic version of 201, so good for LSD transaxles but offers improved shift quality (I've always used 201 in my own 951 with LSD, shifting a tad notchy when cold, but great wear protection for track use). 202 is pricey but worth it, has even been a worthy band-aid for worn second-gear synchros on a couple of customer 951s.

Greg Brown did my LSD way back maybe 12 years ago. The Quaife diff had a bolt that backed out and trashed the case sawing a hole in the bottom. I will never buy another Quaife, customer service is horrid. Absolutely no fault of GB. It was a sweet tranny while it lasted. Anyway GB said Mobil 1 75/90

Very timely topic, as I'm wanting to change the fluid in mine as well.

Anyone have experience with Amsoil 75/90 Severe Gear Oil?

Cheers

Gaspowered wrote: Thu Jun 12, 2025 8:34 pm Very timely topic, as I'm wanting to change the fluid in mine as well.

Anyone have experience with Amsoil 75/90 Severe Gear Oil?

Cheers

I love Amsoil's Severe Gear (all their products actually). While I've never used it in my Porsches, I have and continue to use Severe Gear and Signature Series syn oil exclusively in other vehicles such as my GMC. Their filters are top-notch too. I used their products exclusively back in the day for race and track cars too. Great product and great company.

Motul gear competition 75W140.

It's nice to see such a strong consensus.

Ignore the recommendation for use in Fords. It works fine for other makes too. Coats and Cushions the gears for quiet operation.

I'm on the lookout for Red Line MT90 75W90 GL-4 0.94l RD-50309 but I don't have a LSD transmission.

I use Red Line MT 90 as well, but I too have an open diff. I believe it will work with an lsd, maybe you'll need an additive. Definitely check, I'm not 100%. Anyhow, I love how the shift feel is, even when cold it still shifts great. It doesn't smell bad, and it's even a nice color! It transformed my transaxle. One thing though, if you have been running a thicker oil like swepco 201 and there's wear in your trans or differential gears/bearings, the mt90 won't mask the gear noise like the swepco did.