switching to synthetic...filter change intervals

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Jul 30, 2002
richmond, va, usa
I remember a post a while back where Terry Dyson said that instead of flushes, he supported changing to synthetic with early filter changes until the engine was cleaned out... The general question to anyone is...how often should these filter changes be made. I changed to Amsoil in an engine that had 40,000 miles on conventional oil. I did flush it with the Amsoil flush, but am thinking about changing out the filter early, I have two Amsoil filters on the way, so I am not worried about wasting the existing filter. should I change at 1000miles? when the oil is black? 3000miles? thanks I was not sure if this should go in oil or filters, so if it should be moved, feel free.
Matt, Since you have flushed this engine, it should not be necessary to do an early filter change. If the oil gets very contaminated from cleaning deposits, you will notice a significant increase in oil consumption. If that occurs, I'd change the filter at that point and topoff the crankcase. The oil should stay pretty clean looking for 7k-10k miles and then start to darken very gradually .... As I recall, you were running a 15w-40 ...what sort of hot oil pressure do you see at idle and at speed?
yes, I was running Delo 15w40 and went to Amsoil AME 15w40. Spec oil for this engine is 10w30. I have the stock ford "anything over 8psi is good" idiot guage, so no real answer to your question. I have a mechanical guage on the workbench now, but am pondering a digital guage...
I wouldn't do anything special. I didn't used to do oil analysis. But what I would do now is take a sample at say 5K and change filter. One the other hand, if the oil got black earlier-I would change oil and filter. I'd probably take a sample also. Just MHO. [freaknout]
Originally posted by TooSlick: ... If the oil gets very contaminated from cleaning deposits, you will notice a significant increase in oil consumption...
Just curious about the mechanism behind that... I'm not so sure I believe it, but then again who am I to argue. It is interesting at least. Maybe that could explain the high consumption on the first run of M1 SS in the Jimmy?
If you are switching from Delo, you will not see much, if any, cleaning of residue, as Delo has a higher detergent/dispersant than most oils. When I switch people from a CC or CD oil to a CI-4, or SC to SL I see huge cleaning. Consumption with switching is normally only when moving from an oil that left a lot of carbon on the rings that kept them from moving well, or varnish on the walls that begins to clean up. possibly deposits on valves. But it is more the exception than the norm.
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