Synthetic Oil and Extended Drains....Data!

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For those of you riding the fence on sythetic engine oil and extended drains I wanted to pass on some recent oil samples that may help you decide.

I have sample my engine oil every 6K for over 160K miles. First with PB2000, them Amsoil 15W40 and recently Amsoil 5W30. Since switching to synthetics, I decided to run 4X as long or when Iron reached 100ppm to help justify the cost. I change oil filter, and sample every 6K but only dump the oil every 24 - 26K miles.

In all my past sampling, the worst samples came back when the use for that sample was many short trips, wintertime, and little or no pulling. Samples that had very hard pulling, high oil temps, EGTs, Boost were some of the best samples.

My most recent sample I would categorize as one of the most abusive based on the above findings. I had 24K miles on the oil with the last few thousand being the month of December. December here in ND was the 7th coldest on record. I did no long trips or pulled anything for the last 50% of the 24K miles. My oil temps never reached 180 degrees for the entire month (with winter front, no fan). Drove everyday.

Values for the fours sample intervals are as follows (6k,12k,19k, and 24K):

Iron: 32 - 42 - 51 - 55ppm
Silicon: 7 - 14 - 15 - 12ppm
Visc 100: 10.8 - 10.7 - 10.7 - 10.5
soot: .1 - .1 - .1 - .2
TBN: 11.4 - 11.1 - 9.9 - 9.7

Again, No bypass filters, just Stratapore changed every 6K. This is the second 24K interval with the Amsoil S3K 5W30. The last was just as good. The 15W40 would reach 100ppm iron at the 24K point, but I am starting the think the quick oil pressure one gets from lighter (5W30), synthetic makes a differece, especially with below zero starts for thirty days straight. As fars as 5W30 and summertime, the above sample as from May 2000. I had lots of hard, hot pulls over the summer.

BTW! The Amsoil air filter had 70K miiles on it. My Silicon was on the rise so I changed it prior to getting back these results. I had never open it for the entire 70K, and my filter minder never moved either (I can move the minder with a stock air filter and WOT at will). I am amazed this thing still flowed air. It had a solid coating of oil+dirt that you could pick off in chunks. The above oil samples don't lie nor does the filter minder.

If you are like me, you have to prove to yourself products work. For my application they work better than I expected.

jjw
ND