1985-1998 [Subscribe to Daily Digest] |
The purple cast to the oil disappears to a brownish tone after a short time, and mine always looks like it's ready to change. RP is dark when new and stays that way, so don't use this as an indicator.
As for your low TSB, I wouldn't be surprised if you tested during the first change to RP. A friend changed from Mobil 1 to RP in his BMW motorcycle (Boxer engine), and experienced a low TSB after only 3k miles, having used M1 for about 50-60k before that. The deposits that showed up in the oil indicated elements that weren't present in RP oil, and the recommendation was made to change frequently for several changes until thoroughly cleaned out.
RP recommends a quick change (3k) immediately after switching from another kind of oil, but from what I've seen I'd do two, maybe three depending on how old the engine is and its past history as regards oil type and change intervals. From what I've gleaned, RP has extraordinary detergent and dispersant properties, and whatever is in there will get cleaned out, maybe too rapidly at first and causing low TSB's for a short time as you experienced. But that should improve with time--and once it is clean, it is very clean.
With the previous owner, my '95 Aero ran fossil oil for 35k miles with 5k intervals, which is marginal at best. I changed immediately with 15w40, then changed again after 3k and lab testing that oil at 5k. Everything looked good, including TSB, so I went to 10k and tested again. At that point TSB was fairly low and a change advisable. There was evidence that it was still cleaning the crud from 35k of fossil-oil use, but I've settled on 10k oil and filter changes from here on out, thinking that if it was okay at that point it'll be even better later.
BTW, if you do test for glycol, be advised that the lab I used in Houston shows "<.05% glycol" on the test sheet regardless of whether glycol is present or not, but that doesn't mean glycol is in the oil! It merely means that the minimum they are able to discern is .05, which threw me for a loop when I first saw it.
Please reply back and give the complete history of this car as regards oil changes--like how many miles on the car, when you changed to RP, how many changes have been effected, what was used before, etc.
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