[Walt Fricke]

I won't get into a "what's the best oil" discussion. Cars ran pretty well on dino oils for years as long as they and filters were changed frequently. No reason they shouldn't still. However, synthetic oils possess a consistence dino oils really can't match.

At a tech talk at the 2000 Porsche Parade in Sacramento, a Mobile Oil engineer explained where synthetics came from. The B29 bombers had a problem landing - the grease in the axles of the wheels hadn't thawed from their high altitude flights when they touched down, so a lot of tires were flat spotted. Mobile came up with a synthetic grease which either didn't freeze or thawed a whole lot faster. Part of its magic was the fact that the molecular hydrocarbon chains (polymers?) were all of the same length. Turns out, they were also more resistant to breaking and getting shorter as well. Which is why oil change intervals these days are longer generally.

The big differences between brands are the additive packages, which neutralize the effect of contaminants which get into the oil from the combustion chamber. These in effect wear out over time. The actual lubrication function apparently doesn't really degrade much. These packages are proprietary as each oil company's chemists strive for a better mousetrap.

The most recent issue (now not all that recent) is the level of zinc in the oil. Environmental concerns led to reductions, but operational concerns - especially in our air cooled motors with rocker arms and not lifters - have led many to find oils promising higher levels of ZDDP. I use whatever Mobile 1 Porsche recommends in our 07 Turbo, and Valvoline Racing oil in our track only cars. I used to use Mobile one there, but they lowered the zinc additive. But others use other oils with no issues either. As with many things about our beloved Porsches, there is seldom any one consumable which is objectively the best, and even where pretty scientific comparisons can be made, many sub-optimal things work just fine too. This is especially true for street cars.

210 degrees just isn't all that hot. Engine efficiency is said to increase with heat. At some point wear also increases, so there is a balance somewhere. Bruce Anderson (RIP) used to say that something (over 210 as I recall) is OK, but 250*F is "too damn hot." Well, the oil I use in our GMC5500 turbo diesel tow vehicle is a Delvac brand which advertises standing up to really high heat - 500 or 1,000 degrees? I forget, but way way higher than anything in my SC.

If you don't own it, I recommend you purchase Bruce Anderson's Porsche 911 Performance Handbook 1963-1998. It is full of nuggets - for instance, he mentions Porsche changing the opening temperatures of the oil thermostats over the years. I've read his book cover to cover several times, and look things up often, but I'd not spotted this until just now - since it was mentioned in this discussion. You'll learn a lot.

Bruce died a couple of years ago. The ever helpful Bruce Anderson who helps guys out here on Pelican is unrelated, but equally invaluable when we have problems and questions.