Hello, i am looking for a safe way to guage how i might be able to do a synthetic blend oil change with a 7500 OCI. My car is a 1991 Mercury Cougar XR7 with a 5.0 litre V8. I used Super Tech blend 10w-30 for the last 30K and changed the oil at 4K intervals. At the time, i was afraid to use more synthetic oil in the engine because i had 5 leaks (that was before super tech)! Now, the engine has had a "gasket overhaul" and doesn't leak a drop. The engine was really clean with no sludge when it was apart. It doesn't smoke during start up or under acceleration. I called Mobil and Amsoil to get opinions and they seem to believe that i could switch to a full synthetic mix. I just can't believe that, it seems like a i need a little dino in the mix. My mechanic suggested a mix of 4 Qt.s of 4X4 Quakerstate blend with 1 (maybe 2 if no smoke) Qt of Quakerstate advanced full synthetic with a Wix filter. It's silly, but i ride my bike everywhere for short distances, so mainly the car is for longer duration trips. I am moving to GA where it is already 86* according to my wife to be! What are your thoughts on this? I know nothing of the talk on Group III and other terms.
7500 OCI for 110K Ford 5.0L
- Thread starter SinistreMinistre
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If you're unfamiliar with Auto-Rx, then I suggest doing a search on it. It will help clean up any false seals that may be in there, because with that age/mileage I'd do a clean/rinse cycle before switching to full syn. It might not be a sludger, but you might have some false seals that could leak later on down the road. If you say it's clean inside, then you could probably run Motorcraft 5w-30 blend and a Motorcraft filter (or Wix if you prefer) for 5K easy. 7500 *might* be stretching it. Full syn could easily go 7500, especially if it's mainly for long drives.
Your mechanic's oil choice is a good one, but you can get get a type II/III blend in the Motorcraft oil for alot cheaper. To go beyond about 4500 miles with an inexpensive oil, you will need to do some testing.
A lot of those 5.0L V8's really like 10W-40. My neighbor with his 1994 Mustang GT, uses Quaker State 10W-40 Blend, and says the motor really likes it.
At 5000 miles get a sample tested and post it. The lab will tell you if it should be changed now or if it's ok for continued use.
Thanks for your help! So what you are saying is that QS blend and Motorcraft blend are reasonally comparable? I found Motorcraft to be 88 cents cheaper than QS 4X4. I think i will definitely pursue a lab test at 5K and see how the oil does.
What do you think about using 4 Qt.s of motorcraft blend with 1 Qt of full synthetic?
Thanks again! I'm not too knowledgable about 5.0L and oil preferences, but i have a friend back home that runs a Ford based speed shop, i'll ask him. With the 10W-30 i don't have any tapping or engine noise. Supertech seemed to do fine, but didn't seem to like a really long OCI, 3-4K was all i would push with the blend.
What do you think about using 4 Qt.s of motorcraft blend with 1 Qt of full synthetic?
Thanks again! I'm not too knowledgable about 5.0L and oil preferences, but i have a friend back home that runs a Ford based speed shop, i'll ask him. With the 10W-30 i don't have any tapping or engine noise. Supertech seemed to do fine, but didn't seem to like a really long OCI, 3-4K was all i would push with the blend.
What was happening that made you drain the oil at 3-4K?
Also, I have a 302 and 351W and both run perfectly on 10W-30. Bearing clearances are not loose in these engines as they come from the factory.
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