G50 and Royal Purple GL-5 Maxgear oil.

Vino · 12:36 PM

Hey Guys,

I was wondering if any of you have ever used Royal Purple "Max Gear" 75w-90 in your G50 gearboxes?

I asked since I have tried Mobil 1 and Redine in Different cars, BMW M3, Toyota, and VW and never felt a better oil than Royal Purple.

My M3 felt great with redline cold but terribly notchy when hot, it was D4-ATF.
When hot I almost felt a small grind in each gear. BTW, the car only had 20k at the time and was a pampered car.
Went with RP Synchromesh and it was extremely smooth, warm or cold, and it gets cold here. Was better than new. I did the "Max Gear" GL-5 approved in a Toyota and VW that are known to have terrible 1-2 shifts with amazing results as well.

Anyway, I bought the oil but would like to hear some experiences from some of you guys since I can return the RP if not used.
If nobody had experience with it I'll give it a shot and fill you guys in on what happens

Bill Verburg · Bill Verburg's Garage

Some have used the RP and RL, AFAIR they worked ok.

Most knowledgeable people have been using M1 SHC. This is not the M1 that all the jobbers carry. Often it can be found at a hd truck or equipment shop.

SHC has been discontinued, it's replacement is Mobil Delvac Synthetic Gear Oil 75W-90. Again not available at Pep boys et al.

cnavarro · 10-09-2007, 01:09 PM

I have used Royal Purple Max Gear and it has smoothed out many a cranky transmission. I had someone local to me with a 915 that would go out of gear and that also moaned and he put RP and has been fine the last three years, not a single problem again. I run the Delvac 1 Syn Gear oil (Mobilube SHC) and I am very happy with it's performance, at least compared to Redline in my G50.

Vino · 10-10-2007, 02:59 PM

Thanks guys.

I'll give the RP a try, if it makes things worse I will move on to the Delvac gear oil.

I plan on driving year round if weather permits, so cold shifts are a bit of a concern.

GBOX · 10-11-2007, 02:37 PM

We have been experimenting with gear oils lately to try and prolong synchro wear in the 996 and 997 gearboxes. We have found that in at least that application that a synthetic oil can be too slippery for the synchros to due their job. The oil forms a terrible film over the synchro rings and actually leads to burnt up dog teeth and sliders. The gear oil does not allow the synchro ring to lock on the gear and slider spining them up to match their respective rotational speeds.

I try to stay out of the gear oil game, as it can be very owner and application interpretive. Redline seems to be a bad choice from what we have gathered and we are trying numerous lubricants to find one that we can reccomend for every application, but it that's just not the case. It seems that a synthetic can smooth out an old trans, or burn up a new one in race conditions and Valvoline 75-90w works well in anything.

Here are a couple lubricant that seem to be working very well.

Shell => Spirax and Helix model, used by Porsche and Ferrari, F1 racing.

Gm part # 12377916, working very well with Mitsubishi owners (GETRAG gearboxes) and also works well in applications when there is a fiber lined or organic synchro surface.

Just some thoughts and possible avenues to pursue for you gents. Take care,