Originally Posted by AZhiCntry
Amsoil has had diesel trucks go 300,000+ mi on the same oil with just filter changes, additive package added at needed intervals and oil analysis. The oil is capable. It's the additives and filtering that determine change intervals.
OK, had this conversation before so please try not to get mad...
I have sat in rooms with some of the most brillant engineers in the world and this conversation comes up from time to time. Now I can admit that AMSOIL has higher detergent contents etc for longer drain life HOWEVER unless you are going to have the oil analysis done half way through each oil change cycle, the guys who know will say that that you just can't do this.
I am not going to talk about the way AMSOIL markets themselves but here is a good link with the actual chemical breakdown of the OILs (AMSOIL vs Mobil 1 then a good comparison chart of some other popular oils).
Amsoil lab test results • Speed Talk
Now here is what the engineers say: Yes with the added detergent and higher quality synthetics on the market today you can safely go longer than a standard oil change interval. HOWEVER as manufacturers have uped the time interval based on some of the base stock improvments in the oil, Synthetics of any kind are simply an added protection. This is especially noted in that some manufacturers are not having the best of luck with these new extended change intervals and the fact the "some" manufacturers have brought the vehicles back and changed this reminder as the GF5 oils simply are not lasting.
Most important part the Engineers have to say: Yes the detergent technology is helpful in suspending contamination in the oil, however NO filter will remove all of this contamination and it will continue to build. Based on varied environemental, temperature and driving conditions the ONLY WAY the oil can be cleaned is to be removed and replaced.
Really what they suggest is you can have the most detergent laiden oil in the world but there is no filtration system in the world that can pass enough oil for an engine to use and clean it completely.
So yes, I can admit AMSOIL is likely a higher quality oil but no one should be running thier oil out to 25,000 miles because if you aren't doing the analysis every single time the environmental and driving changes are going to often cause that oil to not be protecting as it should. on the other hand if you pay to have the oil analysis done as often as needed then you are missing any savings on running this way.