GT John There are two things that will kill any oil. Time and heat. Oil sitting on the shelf For a year is just as bad as oil that has been in your car for 3000 miles. Although the additive package for Amsoil 'May' be the best, It's more of a matter of how long that oil was sitting on the shelf before you bought it. Oil is kind of like aspirin, the fresher the better. Aspirin is aspirin mo matter who makes it, I buy Bayer aspirin because it sells the most, which means it's the freshest. I buy Pennzoil because it sells the most which means it's fresher. When Pennzoil and Amsoil come from the factory they both have to meat API regulations for additives and they both have to have minimum API numbers to be sold in the US, these numbers are uniform for all oil manufacturers, Now Amsoil may put additional additives in there oil for whatever reason, But , I wouldn't guess that would make them better. More like , more expensive. When Buying oil, there are two important things to look for, The API Donut that has the right classification (In your owners manual) for your car, and the manufactured date. Pennzoil and Amsoil are both no good if they have been sitting on the shelf for a year.
Oh yea, I forgot, A filter that filters 98.7 % is nice , unless you put your foot on the floor. then the filter is so good that the oil can not run threw it fast enough, so when you have your foot on the floor, your system goes into bypass, which means you have no filtering. You could put 20 filters on your car, that don't mean it's good.
The reason for my post was to provide information to the interested reader, thus allowing the same to make an educated decision as to what oil and filter to use and why. Facts and Data.
For normal driving use a good oil and filter. If your going to run your car at WOT use a racing oil (no detergents)
Do some research. Compare VOA (virgin oil analysis) of different engine motor oils.
I quit using Mobile 1 5w20 full syn becuase of the UOA (used oil analysis) reports I had been seeing (high iron) which indicates that the oil is not working as well as expected. This is due to the additive package in Mobil 1.
My switch to Redline 5w20 and its additive package will hopefully reduce some of the wear numbers. Wont know until November when I change the oil and send a sample to Dyson Analysis.
I also use a FilterMag on my oil filter (the 300lb model). Wont know how well this thing works until November when I change the oil filter. I'll cut it open to see if the mag has done its job.
Yeah this is an old thread.
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2005 Mustang GT - Automatic WMS 80mm HV Intake System SCTuning by Doug@B A M A chips WMS 80mm 93 Octane Race / Tran Tune BMR Front Sway Delete, IMCO Extreme Axle Back Exhaust, Saleen SS UDP's, PH Aluminum DS, Steeda LCA's, Steeda UCA, FRPP 3.73
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RE: 5w-20 oil? Keep or change to 5w-30 - 
