Myles Maycher

Goughary

I had been using redline- but switched to delvac after so many recs here. I'll be switching back to redline when it's time to flush it out again. Not happy with the cold performance of the delvac.

Summer time delvac was fine. But i prefer to not have any concerns.

koenig_roland

i am using castrol limited slip 75W-140 for the G64.00 box and the front diff. I do change those fluids every year (at least two years). That`s max 10k KM..
the performance when it`s cold is "ok". At the racetrack, it improved everything during the whole day... No hard shifting in the end of a trackday when everything is hot... it just works.

LM964

For myself I've tended to stick to Swepco 201 80w90 oil for both front diff and gearbox for the last 10 years. Just seems the gearbox is smoother when changing gear (any temp). Not the cheapest but very happy with it. But not the easiest to source in the UK.

newsboy

Redline for10 years. Helped smooth out my shifting.

GTgears

People commenting on shift quality are NOT talking about the front differential. The front diff isn't part of the gearbox.

For the front diff I would use Mobilube HD Plus 80w90. If you prefer Redline products their Gear Oil 75w90 would be fine. And while I generally recommend changing the gearbox oil ever 10-15k mi, you can go 20-30k mi on the front diff and not worry about it.

chsu74

Researching this to replace fluid. Pic of the manual spec.

LM964

Stuck to Swepco 201 tbh. Never had any concerns, all good.

Goughary

I've used redline and delvac. Delvac works fine in warm weather but i prefer the redline as it does a better job in winter. Use the same for trans and diff. Regardless any good quality 75/90 will be fine. When we get into specifics abt which is better - it's always needling in this case as it doesn't make that much difference. High quality 75/90, and done.

JasonAndreas

There is actually a noticeable difference in shifting when using different fluids, so what did Porsche see back in 1998 when they pulled the GL5 recommendation for the 964 and 993 G50/G64 and ONLY for those two? The previous model G50s were unaffected.

Goughary

Yes i know...i feel a difference btw delvac and redline...

But - as to what's best, there are a few that have been Recomended on rennlist many times, and they all are "fine". That said, i have delvac in my car at the moment and prefer redline and will switch back on the next change.

Navaros911

I used redline and a few months later started to have shifting issues. That does not mean it is related to that, but from now on I use what the Porsche dealer uses.

No issues with it. Porsche does test their stuff... and then charges a little extra for it.

I used RL in other cars with no issues.

What I can say is that the Porsche fluid shifts smoother in our super hot climate than the RL stuff.

chsu74

Redline 75W-90 comes in two types; one with LSD friction modifier and another without. C4s have to use the one without.