Steve Weiner-Rennsport Systems

Just remember, what works in the water-cooled 4-valve engines is no automatic guarantee that its the right product for the air-cooled 2-valve motors. I've seen the folly of all that and its very sad because its really avoidable.

Oil just isn't simply "oil" and there are MANY difference in base stocks and additives for every individual application. Just make sure whatever you use contains sufficient ZDDP to protect these older engines since the consequences can be expensive.

Matt Lane offered some sterling advice; talk to people who have been rebuilding these engines for some time and solicit their input. These folks have seen it all from the other side.

NP993

The rockers chew the lobes off the cams, basically.

M. Schneider

My bad. Our 993 has never had a SAE 5w-30 fill although the vehicles operation manual does call for a 5w-30 weight oil in specific climates; temperatures "mostly lower than 14F/-10C" end quote. (actually, can't remember purposely driving the 911 in any MN winter.)

Minny, MN get's pretty dang cold,,, and can stay below neg - 0 *F cold for months at a time. Pick a suitable oil weight ... but it ain't 20/50 V-Twin Mobil 1. (nor is anyone suggesting this)

Dr. No

Thanks.

Now I have another possibly stupid question or two.

I understand the need for the right amount of secret sauce in whatever viscosity oil we use. But I also keep hearing that the majority of wear on an engine takes place at start up, which makes me wonder about optimal viscosity.

So, all else being equal, shouldn't we want a 0w-X or 10w-X instead of a 20w-X because it will flow through the engine faster at startup?

Is the consensus that an xW-40 gets too thin at track temps and a 50 or better is required?

I note my owner's manual says to use only viscosity 10w-40 or higher, although it also approves 5w-30 for low ambient temperature.

Quadcammer

i believe these air cooled engines use a much larger than typical piston to wall clearance, hence a heavier oil weight is necessary at cold start. Thats not to say you need a 20w, but rather that 10 or thicker may be the way to go.

also, from what I understand, using an oil that has a very thin cold weight, and a very viscous hot weight requires a chemical make up that makes it susceptible to shearing. I could be making that up.

JasonAndreas

And yet every 993 left the factory with a 40... And even Porsche Motorsports raced the 993-GT2 with 5w40.

Dr. No

Thanks QC and Jason.

I have read the long LN piece on viscosities and recall the point about shearing too.

I have to say whenever I get involved in one of these oil threads I feel like I did when I took a class on Zen Buddhism.