There are only two food groups:
The foods that require butter on or in them (vegetables, meat, pasta, etc.)
and the other foods (including the all important beer, pickled okra, and other related sub-groups).
My car was an I-95 commuter car for most of 185k miles for a medium-young mother of several young'ins. Maintenance by the PO's was excellent and comprehensive as far as I can tell. It was like buying a new car for $3500 that used 1 qt per 500miles, and had light varnishing with one sticky lash...
Thanks for the tips on the lower viscosity 30 weights. I don't use conventional oil since the PO's of my car used Chevron 10W-30 and it allowed the rings to coke up and the engine to varnish. I have tried the Syntec 5W-30 since they advertise it at 9.7 cSt at 100degC, but the advertised...
I have had similar results to your's in my '96 GT. The engine feels smoother and uses less oil with the 5W-30. But it is quicker and quieter on the 5W-20. I blend them. Optimal oil would be a sticky thick 20 weight in my >>200K mile engine.
Part of the reason the 20 weight oils are better is...
I gave a recommendation based on all the criteria you gave in your original post, and your location. It would seem to me that using an excellent engine oil(s) that will keep the engine clean is your first priority (at OCI).
I have a 1986 740GLE with the B230F engine. The PO's use of 10W-30 car-oil at 3000 OCI worked great except for the coked rings and oiled-out cylinder, heavy blow-by, and severe varnishing with valve noise and dried-out failed gasket set.
If I were to march down to the store right now and get...
Given the fact that the GTX has varnished up every engine that I have used it in, the Mobil Clean 7500 sounds like an exquisitely refreshing and correct choice over the GTX.
The 2-stroke full-synthetic outboard oils and air cooled engine oils reduce the sooting from gas alone. Exhaust system cleanliness is improved over gas alone in my experience. I use lean ratios, like 1:800 to 1:1000 with full-synthetic 2-stroke oil intended for pre-mix (the kind you want).
Manufacturers spec 10W-30 if they think that the engine will chew conventional 5W-30 out of grade or worse. Introduction of 5W-20's that met the Ford spec solved those problems for the 4.6L. Sane oils for the 4.6L are thin 30's and thick 20's of highest quality.
You need to be careful of the 10W-30's in that they may just be an inferior version of a 5W-30 in a given line of oils. Look at the densities, 100degC Kinematic viscosities, and NOACK values. If you are not sure, definitely choose the 5W-30 oil. If you are looking for a better summer oil, you...
If you have been using a top-shelf synthetic like Mobil 1 5W-30 for the life of the engine you will probably never need a high-mileage oil. There will be nothing to fix.
That being said, the M1 10W-30 High Mileage oil is a thicker 30 weight oil with a more robust additive package. This might be...
If I was driving 45,000 miles a year I would want to change the oil quarterly. Thus the Amsoil 0W-20 sounds like a real winner. Reduce the OCI as the engine changes.
If you want to make it to 350,000 miles, then you really need to concentrate on ALL of the fluids and greases. Use a top quality...
Short trips on cold oil is the worst of all possible driving as far as the oil is concerned on street engines. Gas and water contaminate the oil, and the additive package isn't up to operating temperature. I have inherited two engines lately that saw all short trips on cold oil. One is black...
As far as dino oils are concerned, read the blend chart in the following link:
http://www.chevron.com/products/prodserv/BaseOils/gf4.shtml
5W-20/5W-30: blend of Group II+/Group II 20 weight oils
10W-30/10W-40: blend of Group II/Group II 20 weight oils
20W-50: blend of Group II 20 weight/ Group...