Originally posted by Big Jim:
Mercon V is a superior fluid. It is made from much better base stocks that some may consider to be a synthetic blend or some may consider it to be full synthetic. That gives it better charicteristics at extreme temperatures. Mercon V also has an improved additive package that reduces the likelyhood of torque converter chatter during lock-up. Mercon V is a much more expensive fluid to produce. Use it with confidence.

Although I believe in thin motor oils, and I use 5W20 on my Escape, I can't quite bring myself to use 5W20 on my SVT. Basically, I believe in using the oil viscosity that the engine was made for.

That said, 5W20 tends to be a superior oil. The actual viscosity is on the high side of spec for 20 oil, where most 5W30 oils are on the thin side. Motorcraft 5W20 is nearly as thick as Mobil 1 5W30 (one of the thinnest 5W30 oils). All oil companies producing 5W20 meets the stricter Ford specs for blending oil oil so that for the most part any 5W20 is blended to the higher side of the API and ISLAC specs.

Unless you are drive your car in an abusive manner, 5W20 may be superior to 5W30. I drive in an agressive manner, but not abusive, but I still can't quite bring myself to use 5W20 on an engine with a lot of miles on it that started life with 5W30.



Thanks, didn't mean to quote the whole thing but you made some very valid points. The reason I ask is probably because the standards changed and IMHO it was basically to try and raise it's reliability and performance to the levels that Honda/Toyota have achieved without spending a lot of money. I will be using mobil 1 5w20 (I could win a CORVETTE!) and synethic mercon V for tranny when I do the WHOLE SHEBANG before the end of the month. When classes start, I'll hopefully have finished:
1) Cleaning UIM
2) Changed oil to 5w20 Mobil 1 with high performance/durability filter
3) changed tranny fluid with synthetic
4) changed plugs to either autolites (if i can find some) or iridiums
5) optimize my TB.

When I do get the money to do so, i'll bring her down to the muffler shop for Y-pipe optimization and resonator removal/replacement and if I find one by then, SVT exhaust install. (about $50 or so because I know the guy). But the money I'm saving are for the replacement parts. When hopefully that GB for the heatsheild goes through, I'll have that with a K&N and there, the Mystique.

1998 Mercury Mystique LS - Looking for SVT EXHAUST, SVT Rear bumper (silver frost) and ANY rocker mouldings (side skirts)