stevemainian said:
dont use synthetic.
castrol gtx 10w-30 is the best to use, espically for the miles most SHO's have on them.
Take your car to a ford dealership. They will be the most efficent on telling you if your DIS is bad, which it probably is.
Steve, you must have a buttload of cash. At $60 an hour diagnostic, I'd buy a cheap DVOM and do it myself. Takes 15 minutes to diagnose if it's a component, wires and harnesses may take more time. Either way, Ford will charge too much for this. I'm a college student too, trust me, it's a lot.
As for Castrol GTX, it's part synthetic, thus containing regular dino oil. Dino oil does not flow as well when cold and does not prevent wear like full synth does. Personally, I reccomend full synth and Mobile1 is my personal favorite. It does not allow ANY wear (which is why it cannot be used as break-in or rebuild oil) and I think it is important in an older engine.
If the seals have been exposed to dino oil for over 100K miles or are leaking already or something like that, of course, stay with dino oil. Synth will just make the leaks worse or may not seal as well (worn out seals hold better with thicker, dino oil).
Mobil1 is used by a majority of manufacturers, especially European cars. The oil has been proven not to have viscosity breakdown until over 15K miles. In fact, Porsche, Audi, and VW scheduale services (oil changes) only every 15K miles!!! Unfortunately, they do not use Mobile1 oil filters, so the filters deteriorate before the oil change. Thus, we usually change the oil in the Porsches every 7500 miles and I believe Audi Reccomends the same.
If you use 6 QTs of Mobile1 over 15K miles and ONE Mobile1 synth oil filter, the price comes to about $40. Now price out dino... not that much more expensive, huh?
All I can say is that I use Mobile1 and the previous owner did the same. I can eat off of my camshafts and the crankcase is squeaky clean. From the filler cap hole, it looks like there was never even oil put in the engine its so clean.
Just stay away from Quaker State. Can you say carmelization and funky orange color? Bleach.