Dennis Haynes wrote:

>>I don't think synthetic oil will be all that helpful for passing
emissions but there is no doubt that it has benefits. I have been doing
oil testing on my vehicles now for about a year and there is no reason
not to go 7,500 miles between changes with a good synthetic so unless
you are using a lot of oil that alone offsets the cost. Mobil now
has"Extended Performance" oil they guarantee for 15,000 miles or 1 year.
I think that is pushing things. I did go 13,500 (1 year) in my Fox. My
wife's Audi reports indicate about 12k is the limit for that engine
which now has 179k on it. 2 weeks ago there where 4 Vanagons here with
over 200k on the original engines, (including mine). What did they have
in common? Mobil 1 15w-50. Fun Bus even has the original head gaskets.

Dennis<<

Dennis,

I run Mobil 1 15-50 in my 88 Westy, but I change it every 3500 miles.  I know that theoretically I can run it longer, but my concern is not oil breakdown, it is that the filter will be overwhelmed.  I have been told that oil filters reach their capacity under normal conditions at around 3500 miles.  During the summer I drive on dusty roads quite a bit and that also would put more strain on the filter, I think.  Have you taken filter life into account in your oil testing?

I run Mahle filters.

Thanks.

Warren Lail
88 Westy "Billy Bones"