RallyDogRacing

What is the conventional wisdom lately on gearbox oil for the 964-series and specifically the gearbox on a C2. My syncro's feel a bit lazy even on a warm gearbox so I assume the chain of POs have probably never done a fluid change.

So in older 911's I believe the golden rule is SWEPCO only. But I haven't found a 75w90 SWEPCO available. So is a good RedLine, or RoyalPurple 75w90 an acceptable alternative in folks experience?

Given the car's 113k and relatively easy duty-cycle of commuting (not track use) I was even thinking I could just use any old cheapie GL4 or GL5 spec 75w90 and change it a few times really clean the thing out. I bet $0.02 that what I drain out is going to look a lot like a Venti Latte.

TAI2

Go with Redline as an alternative.

GTgears

The Borg Warner synchros in your gearbox prefer a synthetic gear oil. Redline and Royal Purple are both totally adequate gearoils. Mobil 1 Delvac tends to be the preferred gear oil of many of us, but it doesn't shift quite as well when cold as the other two mentioned. Just be sure that you get a GL5 oil and change it fairly often. On these older cars that don't see as many miles per year as they did in period, I usually use time instead of miles to determine intervals. Change it every 2-3 years and you'll do fine.

Regards,

Matt Monson
Guard Transmission LLC

941MXVET

After we bought our 962 C2, we went through and changed all the fluids to get a base line. I contacted Redline, as I mostly use their products, and was advised on which gear lube they suggested, which was their 75w-90ns. I've been pleased with the performance of Redline's product line.

BTW, the 75w-90ns is a GL-5, GL-6 lube.

RallyDogRacing

Changed out all the fluids this weekend (engine, trans and brake) and things are mucho improved. Gearbox oil while not in full Latte mode, it was still quite 'sparkly' and clearly worn out fluid. Engine oil and brake-fluids were similarly ready to be changed out.

Thanks folks.

surfdog4

I haven't done my 964 yet, but when i changed out the fluid in my 944 (it wanted GL-4) with Royal Purple the shifting was much smoother (especially 1-2). I was going to do the same with the 964 but couldn't break the *&#$% fill plug loose (the 17mm hex on the 944 and 928 was bad enough, but 10mm??). Anyway, it's waiting for me when the weather warms up some

SilvA4Q

Rob, what did you end up going with? I think its about time for me to replace the fluid in the Cab. Did you have much trouble breaking loose the fill or drain plug?

RallyDogRacing

No breaking the plug loose was easy. I popped the fill plug first, then the drain plug. I ended up using Castrol Synthetic 75w90 which is a GL-5 spec synthetic. It was 60% the price of RP, and I figured I would be doing at least 1 more change at the end of the season to 'flush' the box. THere was a significant amount of build-up of material on the magentic plug so I don't mind running with temp-fluid in the shorter-term. That being said, the shifting improved a LOT even with a budget synthetic GL-5 spec fluid. So I will not be in any rush to swap it out urgently. The improvement comes mostly from fluid with all its lubricity and shear-life left in it and being clean; vs. the 20yr old junk in the gearbox.

SilvA4Q

That's good. Mines been a little rough shifting between the lower gears and I'm starting to think that the oil is past it's prime and needs to be replaced. Did you use power bleeder or mityvac for the brake flush? That's also on my "to do" list.

On a separate note, are you going to make to the TAG track day Saturday? Now that the Targa is back in slick shifting condition it would be nice to take it up there.

Laker

+1 I notice a little more notchiness from 1st to 2nd and 2nd to 3rd for the first minute or two on a cold engine. Even though the old stuff replaced was black coffee colored and probably original... no complaints, but next time will check out Royal Purple.