When to change to synthetic oil on factory remanufactured engine?

I had a new engine put in a 1999 F250 Super Duty a year ago. That was a situation and related to a dishonest and incompetent mechanic that I used. Anyway, the truck is only has like 4000 miles on the new engine and has had one oil change since what came in the factory fill at like 500 miles. I figure it is due for a change.

I have 2 jugs of Mobil 1 5W20 Truck and SUV oil on hand, whatever that means, plus a filter. What is the difference between this oil and car oil?

Anyway, several people have said I should have just gone to synthetic on the first change and it wouldn’t hurt anything and others say I should drive it longer before changing from conventional to synthetic. Any opinions on this? It is a factory remanufactured Ford Motorcraft 5.4L 2 valve engine if that matters.

Seems like it’s just a good oil:
“ Mobil 1™ Truck & SUV motor oils are designed for gasoline-powered trucks and SUVs and are recommended by ExxonMobil for all types of modern gasoline-powered vehicles, including high-performance turbocharged, supercharged, multi-valve fuel injected engines found in passenger cars, SUVs, light vans and light trucks.”

Just go get the oil changed with whatever viscosity the original owner’s manual called for. Synthetic is fine.

Don’t overthink this.


IF it was me, I would put in the oil you have and then switch to synthetic after that on your next oil change.

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Mobil 1 is synthetic motor oil.

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Yep, thanks. Lack of sleep. :laughing:

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I had a really good experience with synthetic oil.on an air cooled lawnmower engine. I bought the mower in 1992. The manual calls for 30.weight heavy detergent oil for the Briggs and Stratton engine. Three years ago the mower was using considerable amount of oil and was puffing clouds of blue smoke. I decided to try synthetic 10W-30 oil.in the engine. At my Rural King farm store, the straight 30 wright non-synthetic oil was $1.79.a quart and full synthetic 10W-30.eas $2.79 a quart under the house brand label. The synthetic oil cut the oil consumption by 75%. However, late last summer the oil consumption went up again. The synthetic oil bought me almost three more seasons of use. I think it was worth $1 a year to go to synthetic oil. I will probably go to a battery powered mower this year. Toward the end of the mowing season I was wearing my N95 face mask when mowing due to the oil smoke.

I have had several small abused/neglected engines really come back to life after switching to synthetic oil. I would maybe try Rotella T6 15W40 in one that calls for a straight 30W and see what happens. This is a high detergent oil and can help clean out deposits left in the rings, etc.

I have had several mowers that would just bog down and smoke until I swapped to the Rotella T6. I have also used the 5W40 flavor on other outdoor engines calling for 10W30 with great results. I seem to come across people dumping old mowers that just need the carb cleaned quite frequently. Many of these are all sludged up of course but the rest of the mower is fine. Some run like a champ after an oil change and others just fly apart rather rapidly with the new cleaner oil being thinner than the sludge the engine had worn into.

If buying a new mower, I would buy one now to avoid not being able to get one.

I am definitely a believer in synthetic oil and feel the extra cost is worth it. I buy on sale to get several at a time and it really isn’t much more than conventional with me doing it myself. Oil changes are one job where it actually saves time for me to do this myself than to make an appointment, take it in, etc. I am just more concerned if the new engine is broken in enough to be changed over to synthetic.

The oil I have on hand is this. I am not sure what the difference between regular car oil and truck/SUV oil is but this is a truck so why not? It was the same price.