912 Registry :: Gear Lubricants

From: Jon B. Kanas; kanas@quality.qadas.com; I have a 1969 912 with around 200K miles, original transmission. When I purchsed the car in 1981, I noted that the syncronizers were rather weak. I converted the transmission to Amzoil 80W90 and the syncronizers quit working entirely.
I contacted a Porsche transmission specialist in Denver (now retired) who said that the syncronizers rely on a certain amount of friction to operate properly, and that the synthetic lubricant was "too slippery". I changed back to conventional 80W90 gear oil, and the syncronizers returned to the normal, albeit weak, behavior.
Jon Kanas

From: Gavin; gavin@gavinjouledesign.com; Rick, I have been using CASTROL EPX 80W/90 DIFF GEAR OIL. This is in the UK and all seems to be well, it was recommended by our UK guru Andy Prill.
Do you change gear oil in the drive like me? Are you are worried about getting correct amount in there? What I do is trolley jack up the back end overfill let down with plug out, drain excess and refit plug. This does however rely on your driveway being pretty flat! Gavin Joule PCGB 912 Register

From: rdburn@meer.net; On my '68 912 I have always used Castrol 90 wt gear lubricant. After 235 K miles I have never needed to do anything with the transmission; I religiously change the trans oil every 6K miles.

From: jfrost@jackfrost.com; I use Red Line MTL in my 1966, 912 transmission. It works perfectly, no notchieness in shifting or anything like that. Do not use any other Red Line product or it won't shift properly. Red Line adds a special friction modifying component to their MTL which matches that of the original oil specified for the transmission. Without it it is to slippery for the syncros to work.

From: smith244@llnl.gov; Hi Rick, I've tried Swepco and it really made my shifting stiff. I tried Amsoil in a couple of my Porsches over the years and I have no complaints. I use Redline now and my tranny seems to be much happier. It's still a little stiff at times but on the whole my temps are better, it shifts better, and my seals like it much better than other synthetics. Synthetics stay cleaner longer too just because they don't have the ash and other solids to gum things up as time wears on. -Chris Smith '76 912E

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