Flint

I just changed my oil, went to a 10-W30 synthetic, new filter, crush ring, everything. After a couple of days, I've noticed a consistent drip right from the drain plug. I've tightened it up a couple of times, but the drip is still there. Now, after seeing the thread about particles on the drain plug, I'm suspicious I don't have the right plug. It looks nothing like just a big, 30mm bolt. So, I'm wondering if this is a jury-rigged plug that only "seems" to fit and the lighter weight oil is just getting out more. But, that's just my thought. I'm only worried because I'm taking the car on a 300+ mile trip this weekend. Any ideas?

Normy

Ok...this is just me, but how warm was it in Omaha today?

You put 10W-30 into your sump in the summer? Why? That stuff is for Alaska or Finland or someplace north of Jacksonville in the winter~

I also have what is apparently a plug. It probably wouldn't hurt to call the big three to see if they have them in stock, but I don't think it matters that much.

Normy!
'85 S2 5 speed

Mike Schmidt

The Porsche approved engine oil bulletin shows synthetic 10W-30 is okay up to an ambient temperature of 100 degrees F.

Flint

Hmm, I think you're right on there. Last time I used 15W50, and I do feel a large difference in the way the engine runs (much smoother now, actually). I thought this was supposed to be a "fuel efficient oil" which in the owners manual covers the range of temperatures that I'm currently experiencing. Interestingly, on the Mobil 1 site, they list a 0W-40 oil for "european cars" which is supposedly factory fill for new Porsches. I certainly didn't see THAT at advance auto.

Well, if it continues, I'll either just change the oil again or bring along a case.

Mike Schmidt

The Mobil-1 0W-40 is still pretty hard to find in the U.S. As far as I know, the most likely place to find it is at a Porsche or Mercedes dealership. Some of them may only have it in large drums though, using it for the oil changes that are done in their service departments.

Normy

Dude- fuel efficient? Come on!

Let me ask you this question: How do you intend to operate your Porsche 928? Easily or strongly?

Relative to other vehicles you own?

-I operate vehicles for a living, some of which are capable of quite a bit higher speeds. We have SPECIFIED oil.

I've been taught that low viscosity oil is better for engines experiencing lower temperatures because it allows flow when it is cold.

I'm like "Omaha in July is likely to be somewhat hotter than very low temperatures...."

-I think that if your oil is VERY NEW it will behave fine in your engine. Porsche tested a bunch of engines and came up with their recommendations. New engines....with new oil. Is yours both of these?

I'm sorry, but I think you need to go to Wal-Mart, buy 9 quarts of 20W-50 [brand of your choice] and redo what you just did!

Lets see now....how much are used 928 motors going for on Ebay? Feel like paying that much? Lets see now...9 quarts of Castrol at $1.56/quart costs $14.04. This sounds a little cheaper is all, but then again, we are not dealing with my car.

Normy!

'85 S2 5 speed

SteveG

Well, something made a difference so it must be the oil, but I'm wondering if your drain plug gasket is flat. Manufacturers recommend a new one w/ea change. Some mechanics heat the old one til it returns to original girth and re-use it. You don't mention the year. Some don't recommend synth in older cars because of leakage around other seals that don't normally leak w/dino. You apparently don't have other leakage, but it could still be a gasket problem. HTH.

Andrew B.

About the Mobil 1 oil 0w-40. You can find 5W-40 at any Schucks or Napa, but it's Valvoline Full Syntec. Devek recommends Valvoline synthetic and Redline oil over Mobil 1.

Andrew
84 928s

Sab

Did you change the crush ring on the plug? You are supposed to change it everytime you open the drain plug.
I tried to run on 20W-40 vs. 20W-50 the last time I changed my oil and I noticed my oil pressure to run considerably lower. After a hard drive the oil pressure would drop to just above 1 BAR and would only reach 5 BAR at about 3200 RPM's. I changed back to 20W-50 and my oil pressure is always above 2 BAR at idle and hits 5 BAR at 2500 RPM.
regards,
Sab.

Dan Bise

Back to the drain plug: you may have "just a bolt" in there. The factory drain plug has a very deliberately machined concave shoulder which looks like it would be critical to creating a good seal.

Dan
'83S

Flint

Well, I did change the crush ring, though I was worried it may have gotten bent in transport. I'm not worried about my fuel economy at all, I just noticed the package said that after I bought it, so I checked with the manual to confirm it was okay. Though, the week leading up to my oil change was considerably hotter, and it has only now dropped below 100 degrees (fairly decent 80 otherwise, which is not a typical Nebraska summer). What I may end up doing is adding some ATF to fix the sticky lifter sounds, ordering a new drain plug and ring, then changing back. Good idea or bad?

Bill 86.5 928s

Hey Flint..I also had a small problem with oil dripping from the drain plug on my 84 and found that it wasn't coming from the plug ..I had a few loose pan bolts snugged them up and my problem was solved..Just a thought ..good luck Bill 84 928s

Mike Schmidt

[quote]Originally posted by Sab:
<strong>I tried to run on 20W-40 vs. 20W-50 the last time I changed my oil and I noticed my oil pressure to run considerably lower.</strong><hr></blockquote>

Something else to make the oil topic even more complicated...

Having excessively high oil pressure may not be a good thing. Your oil pressure is higher with the thicker oil because it's harder to pump through the engine. It doesn't flow through there as easily as thinner oil. You may have higher pressure with the thicker oil, but also have a lower volume of oil going through the engine with it. It's also more difficult for the thicker oil to get between the bearing surfaces. If you think about it, why do you have oil pressure at all? Because it can't get through the engine as fast as the oil pump is trying to pump it. The higher the oil pressure, the more of a restriction there is to it flowing through somewhere.

One of the important purposes of the oil is removal of heat. A lower volume of oil going through will remove less heat from those areas that it's supposed to, and the oil may also get hotter since it's moving more slowly through those hot areas. Thicker oil will hold heat and not disipate it as easily as thinner oil will when going through the oil cooler. In other words the thicker oil could be getting hotter and staying hotter as it circulates through the system. Hotter thick oil would break down faster and loose the ability to lubricate as well as cooler thin oil, even if it was able to get into the bearing areas as well as the thinner oil.

Thicker oil will also retain more air than thinner oil will.

Thicker oil being harder to pump also costs more power than thinner oil.

My personal opinion is that using oil pressure to decide what viscosity of oil to use is not a good idea.

Gretch

The racing shop that does the work on my cars uses 15w 50, Molil 1, and my casr dont see winter...