as many of you folks know I have a 99 forester with the 2.5, 123,000 miles and the usual piston slap. The slap has concerned me less and less as it ticked along with a number of you telling me they tick on forever. I added Mobil 1 15-50 in an effort to cut the slap a bit and it has helped. I wanted to make sure that the 15-50 was not too thick and causeing damage, establish an oil change interval, and see how much aluminum was showing up in my oil from the piston slap.

I am going to quote from the Blackstone report.

"We often get samples from people who are concerned about cold-start piston slap problems, though we don't often find a reason for it. That's the case here. Wear looks about as good as one could hope, with all metals in your engine reading around averages for this type of engine. The oil was in good shape physically, containing no moisture, fuel, or coolant. The viscosity was normal for 15-50 oil. With wear looking tthis good, we think you could easily run more miles on the oil. (I changed at 3,890) Try 5,000 miles next time around. Looks like a nice engine from here."

Actually my aluminum was right on area averages and below national averages because we don't have weather as cold as nationally.

The point of this was to see what piston slap was doing to the engine as so many of us were concerned with it. It looks like the Subaru is right and piston slap is not greatly affecting overall wear, at least on this engine.

Thanks for the info. I don't find it surprising. Our piston slap seems to have stabilized, it hasn't really gotten any worse since about 100k miles. I'm curious to see the bearing wear numbers given that relatively thick oil.

 

Can you post the entire UOA? Did you get TBN? What was your driving routine? How long was the oil in service?

 

That is a short run for M1. Here's a link to my run of 12498 miles in my XJ on M1 5w-40. I could have probably gone to 15k.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=003140#000000

 

I don't have any UOAs for our EJ25 or we could do some compare and contrast. I'm sure that plenty of EJ25 UOAs can be found on BITOG. Maybe I'll have the current batch of GC that's in the EJ25 analyzed this spring.

Being a cranky old guy I am not all that computer savy. Send me a pm and I'll give you my email. Then you can send me a note and I will forward the report to you.

Cookie, we need to get the moderators to make this a "sticky thread".

 

Thanks very much for sharing, I for one will sleep a little easier now ;-)

I posted cookie's UOA over on BITOG.

 

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic&f=3&t=003195

This should give us a few comments.