synthetic oil - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

probe_racer82 · 12-19-2001, 22:54

i recently (last oil change) switched oil from regular castrol GTX to castrol syntec blend. i've heard from a few people that its not good to switch to synthetic on an engine that has a lot of miles with regular oil. (mine has 94,000) now i've noticed leaking around some of the gaskets. is it too late to switch back, or have i just screwed everything up?

dmark101 · 12-20-2001, 07:46

don't sweat it.

i switched to synth when my car had nearly 80k miles and i haven't had any problems aside from the normal change of the valve cover gaskets. other than that, which i needed anyway, there haven't been any problems.

i would recommend using mobil 1 5w-30. castrol synthetic is not synthetic, just highly refined petroleum.

tony95pgt · 12-20-2001, 09:05

Yep.. my car had about 71,000 on it whne i changed over to sythn.. i also recomend 5W-30 is what i'm running Mobile one.. i had the problem with my VCG's before the switch.. so i needed it anyways..

Caliguy143 · 12-20-2001, 22:15

im running 10w30 synthetic blend on an engine with 152,000 miles and it runs great.

shouldnt leak because its synthetic. did you use a lower viscosity?

probe_racer82 · 12-21-2001, 12:34

i'm using the same viscosity as my old oil. my valve cover gaskets leaked a little bit before, but seems to have gotten worse since i switched oil.

TakimanPGT · 12-22-2001, 10:57

Which is normal. The VCG's are a day's job for an inexperienced mech. Do it and go full synthetic. I use Mobil1 5w-30 with a Motorcraft filter and the motor purrs like a kitten at 79k and counting. I first changed over at 67k. And just did the VCGs 'cos we had the IM off anyway for some other stuff.

Rose Bud Mist · 01-06-2002, 19:51

I have less than 70K on a 95PGT and switched from castrol syntec 5W-30 to complete synthetic 5W-30. No problems or leaks at first, after about 2K I started noticing I was burning oil, somehow. It was not leaking out anywhere. So I went back to part synthetic with no problems.

Noclss2000 · 01-15-2002, 19:25

I think whoever told you that is toking on something. Synthetic oil conditions seals that are old and worn. It is also easier on the engine that way. dont use a higher viscosity though b/c our HLA's dont' like it too well. I use 5-30 in mine Mobil 1 full synthetic. I go through about 1.5 quarts per 5000 miles. But I have a oil leak in my 2nd cylinder due to the bad VCG.
Switch to synthetic and enjoy a longer living engine.

Noclss2000 · 01-15-2002, 19:26

BTW: my car has 138000 miles on it and I use it. Been using it since my car hit 100k.

TakimanPGT · 02-11-2002, 17:11

Use the Mazda filter! Best one yet that I've seen after experimenting with a lot of them