If car owner's manual says to replace oil 3k/3mo interval, and oil is Mobil DC 5000 which is good for 5k, which will you follow, the car manufacturer or the oil manufacturer?
Theoretical question.
- Thread starter 626LX2.0LATX1998
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How new is say car?
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Unless the car is totally new, how about a 4k mile compromise?
let's say car is out of warranty
On the Mobil web site it says in the first paragraph to follow the manual for the new car warranty. In the second paragraph it says mobil will warranty the engine for the 5k/7.5k/15k OCI. I think I would follow the manual until the warranty is expired.
even after warranty, wouldn't you follow the car's manufacturer since the car is more expensive than oil?
But the oils have been improved over time (since your car's owner's manual was written). I like moribund's solution to split the difference if you're concerned.
The way to know for sure is to do a few UOAs.
The way to know for sure is to do a few UOAs.
Let's say you have extreme cold winter ambient temps. You should use manufacturers(severe service) recommendation for seasons with extreme temps, and Mobil's reommendation for seasons mild temps.
guessing is good enough most of the times when it comes to oil. My guess for most cars under normal mixed highway/city conditions would be 5000 for dino. In most cases with factory suggested 3000 mile OCI, going over 5000 on dino is still perfectly fine. My toyota actually suggests 5000 mile OCI with dino, so people on bitog would probably be going to 7000.
I would agree with one of the guys upstairs, UOA would be the best way to find out.
I would agree with one of the guys upstairs, UOA would be the best way to find out.
I agree with VAD.
Humble estimating says most all modern oils are good for 5K. I would of course make sure my said car was not on the sludge list
Humble estimating says most all modern oils are good for 5K. I would of course make sure my said car was not on the sludge list
Dr. T,
Here is an except from my wife's 97 Expedition owners manual. It specifies 3k mile oil changes for severe service.
Here is an except from my wife's 97 Expedition owners manual. It specifies 3k mile oil changes for severe service.
The manufacturer doesn't know how you'll drive the car or in what conditions, so they are recommending a conservative interval. The oil manufacturer wants to convince you that the oil is very good, so they are recommending a less conservative interval.
The best approach is to do a UOA, the next best is to take your conditions into account, and UOAs of similar engines/oils/conditions here, and make a reasonable guess.
I would personally consider 3k to be overly conservative under almost any conditions, and 5k or so more reasonable on dino.
- Glenn
The best approach is to do a UOA, the next best is to take your conditions into account, and UOAs of similar engines/oils/conditions here, and make a reasonable guess.
I would personally consider 3k to be overly conservative under almost any conditions, and 5k or so more reasonable on dino.
- Glenn
Looks like for over 90% of people, the normal service interval of 5000 miles is good on your '97 Expedition.
1999nick,
You're correct, as far as our Expy is concerned. 5k miles would be fine. However, I have to change it every ≤3k miles, since I have so much oil in the garage. I went on an oil buying spree early in '05 & bought waaaaaaaay more oil than I have room for.
You're correct, as far as our Expy is concerned. 5k miles would be fine. However, I have to change it every ≤3k miles, since I have so much oil in the garage. I went on an oil buying spree early in '05 & bought waaaaaaaay more oil than I have room for.
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