Drain Intervals?? Time and Mileage??

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Oct 20, 2003
Eastern Pa.
Looking to change to Amsoil syns with extended changes. Both my vehicles get regular useage, the wife's Explorer logs about 25-28K per year. The extended changes with their regular syn oil (1 year/25K) would be an ideal match but there is no way I will make the mileage with my F150, only 10-12K per year. Question?? there is also a time limit of 1 year for the oil, What is the time limit for? Isn't the oil stable enough to last the mileage limit on my truck? Thanks.

Sure the oil may last longer than a year, and oil analysis will tell you this - but over a full 12 months with climatic changes alone there will be a lot of condensation cycles in your engine, mix in 12,000 miles and it's best to just change it.

I have left Amsoil (S2K 20-50) in for more than l year, and all was well. But it's not recommended.

I also recommend NOT going immediately to 25K. I would run a gradually extended interval, with an oil analysis, say at 10-15K miles max. If you have dino miles on the vehicles you may benefit from AutoRX clean to really start with a clean engine - not required, but hugely beneficial.

The reason for the one year time limit is to account for variables in driving conditions. If you only drive 10,000 miles per year, but it's mostly short trips, you can see more oil degradation than if you did 20,000 miles of mostly highway driving. Even in these low mileage cases, it is VERY important to change the Amsoil filter after six months and top off the crankcase. This helps keep the solids level in check and the fresh oil gives a boost to the additive levels.

I have used the same batch of Amsoil for two full years on a number of occasions, but I always have it tested after a year to see how it's holding up. More importantly, I understand what those oil analysis results mean and don't have to rely on the lab comments ....

You may be able to get 25,000 miles out of the oil in a year with a filter at 12,500 but I seriously doubt that the analysis, if you did get one, would be decent. Only way to know is to try it and sample at maybe 7500, 15,000 etc and see how the oil is holding up. As to the lower mileage one, no problem, you should be able to go one year under 15,000 without a problem but that is assuming that the enigne is currently clean, operating well and that most of the time you drive it at least 10+ miles to heat that oil up and burn off contaminants. Living in a climate that rarely gets below zero F really helps also. If not you will probably not be able to get one year on the lower mileage truck.
Yeah without doing an OA, i've concluded to jus change my amsoil every six months along with the filter. I only put on 8-10k a year with many short trips to work (2 mile trip to work).

Can i go longer? probably but i'm too lazy to find out for sure.
If you are using the regular 5w-30,10w-30, 10w-40, I think that 15,000 miles/1 year is more reasonable - based on extensive testing in my own vehicles. I'd change the filter halfway through and topoff the crankcase. This will keep the engine cleaner than trying to go 25k miles and you'll still have a pretty good safety margin in most cases.

Any oil will work better if you don' t run it out to it's limits in terms of degradation. I've run samples of Amsoil out over 20k miles, but any oil is going to slowly thicken over the course of a very long drain interval. The best you can hope to do is minimize it.

If you're dead set on running 25k miles, the Series 3000, 5w-30 is probably your best bet right now. It uses an extremely robust additive package and a thicker, more stable base oil than the 0w-30.

Dixie Synthetics
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