SlakkerRacingDev

It seems like a lot of people get tired of talking about oil but not me, I love it. I think it's one of the least understood yet most important keys to reducing engine wear and extending the life of our engines. As Ben Strader, who taught me engine development and tuning at EFI University, always says "application dictates chemistry". And by having your used oil analyzed at labs like SPEEDiagnostix or Blackstone after each change, you can see what oil your engine likes best based on how you use it.

So here's a fun little poll, on a sometimes controversial subject, to get more people thinking about how they care for their engine.

sasilverbullet

There's a guy on Youtube, he formulated the Driven line of oils, he's done extensive testing. The oil pressure comes up about .02 seconds faster when you prefill the oil filter. IMHO, doesn't matter.

https://www.youtube.com/@themotoroilgeek

SlakkerRacingDev

Interestingly, when using thinner oils, it absolutely matters. The testing showed that the wear metals increased when not prefilling for a 5W-20, but they did not change for a 20W-50.

This also correlates with why we recommend heavier viscosity oils to be run in these engines, based upon max oil temps. A thicker oil film strength is able to still protect the rod bearings during momentary lapses in oil pressure.


Watch this video for more information or fast forward to 33:00 to see the results.

Denny Swift

So if it makes a difference on the mid-engine cars where you can actually fill the filter housing because it faces up, why does it not matter on the 992 where you can't because the housing faces down? I guess you could do it on the 992 if you placed the car on a rotisserie and flipped it upside down.

bluebonnet

Pre-filling your oil filter when changing the oil is only effective IF your engine is one of those that take oil from the filter then to the high pressure pump then to the engine internals, i.e., filter on the supply side. When I had an air cooled 911, it filtered on the scavenge side. That is, it filtered the oil upon return to the oil tank not to the high pressure pump. Filling that filter beforehand would have no affect on the supply of oil to the engine. I have not confirmed but believe the 9A1 and probably all Porsche flat sixes do this. So there is most likely no need to fill the oil filter since it is not on the supply side. It will be filled when returning oil to the internal sump.

It certainly won't hurt to fill it when installing except that it is easier to make a mess.

SlakkerRacingDev

On the 987.1’s specifically, the filter is in between the oil pump and the oil cooler. Not filling will cause air to be injected into the system and a brief period of oil starvation to the bearings.

XuTVJet

If the engine isn't under any load at start up and there is still residual oil in the system, on bearings, etc., does this really matter at all that these components don't get full oil supply for a fraction of a second? Seems like we're making something out of nothing.

jscott82

I voted "yes" but realize it is a bit pedantic.... Considering the only time there is ever metal to metal contact is on startup, and that "dry" time is being extended from milliseconds to seconds does not feel good..

But

If it were a concern Porsche would certainly put it in the manual.... if it were a big concern warranty would depend on it...

Denny Swift

There are some who believe that car manufacturers deliberately tell us to do things that will wreck our cars so we have to buy new ones. And some of those people have been abducted by aliens.

SlakkerRacingDev

If using a 0w40(which I highly recommend against), and it causes enough wear to show a significant increase in wear metals on a UOA, I would say yes, it absolutely matters. If running a 15w50, probably not as much. But it’s easy to do and since every 987.1S failure we’ve seen in the last 18 mos has been a spun rod bearing, I also consider it worthwhile to try and make people aware of the little things that help prevent the big things.

Kuro Neko

Depends; if you tuck your shirt into your underwear, and throw salt over your shoulder before you face east with the sun rising, then go for it - fill away!

Mike Murphy

What does ‘significant’ mean?

If I invest $10 and get a 5% return versus an alternative investment that produces 18%, that’s significant. And it’s also trivial and doesn’t matter.

I would like to see exactly how many oil changes are required with two test groups before one engine fails versus the other. Oil changes only happen every 6-12 months. Are we talking decades here or a century?

XuTVJet

But aren't most of the blown motors you see coming in are from cars that are used more on tracks? Sustained high G turns on sticky tires and the known rod bolt stretch issue with the M97 motor would explain most rod bearing failures as well as 0w40 not being ideal for track use. 0W-40 oil seems plenty robust for a street driven 987 though, IMO.

Cemlo

I just bought 0w40 rather than 5w40 by mistake. Do I need to cancel the order while I still have time (there are issues with supply so 4-5 wk lead time) or are you specifically saying "highly recommend against" for track use only? There is nothing I've read that says this will be an issue, although I might be missing something!

Mike Murphy

What brand? In short, street car, 0-40 is fine. Race track car, maybe pick a different oil.

The oil discussion is about pre filling the filter or not.