GC in Ford 4.6 V8

Not open for further replies.
Jun 24, 2007
Land of Lincoln
I'm just throwing this out to all of you for your thoughts/comments. I had 5 quarts of GC that I'd been saving for a project car that has now been delayed for quite a while. I finally couldn't wait, so I used it for an oil change in my 1994 Ford T-Bird with a 4.6 V8 (112,000 miles). I haven't had any trouble starting the engine, and the temp around here has been ranging from 40 to 75 degrees since I did the change about a week and a half ago. However, I've noticed that the car seems a bit more sluggish and not quite as quick in the acceleration department (especially when I'm trying to accelerate while at 40-50 mph). I'm worried that this oil could be too thick for my particular engine's service requirements, but wondered if there was anyone out there that could give me any advice, especially if you have experience with this engine. I don't want to put a strain on my oil pump or start losing performance, especially since my car is 15 years old and I need it for a lot of short-trip city driving to and from work. Any comments/advice would be appreciated. I'm trying my best to be objective and not just imagine these "symptoms" in my car. Thanks.
Last edited:
I know that my 96 4.6 feels sluggish on the thicker oils. Use a thin 5W-30, or a 5W-20 and your engine should feel like a whole different animal.
As long as your mileage isn't trending way down run it out to get your money out of it then change back to a 5W20 or 0W20. I've seen the 4.6's run on 15w40 diesel fleet oils for tons of miles. I wouldn't recommend this, but am just saying that GC isn't going to kill your 4.6.
I'm running GC in my 4.6 right now. It's a '96 Town Car and the first time I ever used this oil. When I first changed it I couldn't believe how sluggish my car became. The car would rev significantly higher on start-up(winter)and I definitely felt like this oil was a poor choice for my car. This oil does not meet Ford's spec for the 4.6 by the way.(WSS-M2C930-A and all retro specs back to our model years)

I have about 2500 miles on it and the oil is still pretty clean looking. It runs better and feels less sluggish than before.
Considering this is a long life oil I might leave it in for more than 6 months / 6000 miles but I'm not sure.

The cleaning power of this oil must be second to none. The dipstick shines like hand polished silver. I have never seen anything like it.

I doubt I'd ever run this oil in the car again. The early symptoms were too significant to make me comfortable with it. Just leave it in for this one time and we both should be OK with it.
Thanks, guys. I was driving around today and it seemed about the same - maybe a little better. I have just over 200 miles on this oil now. I haven't noticed any downturn in my fuel economy yet. I guess I'll just leave it in through the summer, and go back to a lighter oil for my late fall/through-the-winter oil change. I only drive this car about 7,500 miles per year and mostly for short trips, so I do my oil changes at six-month intervals instead of worrying about the mileage on the oil. I usually change my oil late April/early May and then late October/early November.
That 94 bird has the old style valve stem seals, does it use much oil?

A thicker oil may be in order for this car, but as a rule modulars like the thin stuff.
Actually, it doesn't use oil at all. I've always been amazed at how little oil this car has consumed over its lifetime. I'm usually at "full" on the dipstick even when it's due for the next oil change. I'm sure it could be different if I put more miles on this car. It's fifteen years old with 112,245 on the odometer, so that amounts to just under 7,500 miles per year. The thing is, those miles are typically about 10-15 city miles each weekday, with about 50-150 miles over the weekends. That's pretty hard on an engine. My biggest fear (especially in the winter) is that my oil barely ever warms up before I get to work and turn the engine off!
I was at Walmart yesterday and they were clearing out their stock of Q-Horsepower for $16 per 5-quart jug. I bought a jug of 5W-20 (the last one) for my winter oil change, so I guess I'll just swap the GC out at that time. My car's long since out-of-warranty, so I'm not really worried about GC not meeting the Ford requirement. I mean, it probably wasn't even tested for it, right? Since GC is aimed at the European car market, would Ford have even bothered with it? I would have to think it would exceed the requirement anyway, based on an oil having to hold up in cars driving at Autobahn speeds for extended lengths of time.
Not open for further replies.