My recommendation for 1988 Ford Straight 6 truck motor

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Jul 11, 2003
A friend of mine asked what oil I thought would be good to use in his 150,000 mile truck. He has owned it from new and always had the dealer do religious 3,000 mile oil changes. He is a competent restorer of old cars and has decided to start DIY maintenance of his modern vehicles.

He takes excellent care of his vehicles and the truck runs perfectly. Smog tests are likewise very clean. No oil leaks and minimal oil usage. He lives here in Northern California, so most of the weather conditions are mild.

I recommended that he run one of the 15W-40 heavy duty oils such as Chevron Delo or Shell Rotella which are both widely available here. I also suggested a Motorcraft filter as an easy to obtain quality filter at a reasonable price.

He picked up the Delo and a Motorcraft filter today.

Personally I think that for his application synthetics oils would be a waste of money, especially if he is most comfortable with a 3,000 mile change interval.

Does anyone want to try and talk me out of these recommendations?

Nope, you did good John.

Great oil and filter recommendation.
I think your recommendations are spot on. Maybe you can try to talk him into going a little longer on the Delo, especially if he does longer trip lengths. Heck even 4000 miles is a 25% increase
I plan to help him with one of his future oil changes and sneak an oil analysis sample in on him
. With that perhaps "we" can move towards a slightly longer OCI.

I have run XD-3 15W-40 in my 1990 F-150 six since new. Compression, hot idle oil pressure, and cleanliness are like new. Cold starting down to -10F, as cold as it gets here, is fine. The engine has around 220,000 miles, troublefree. I think you'll like an HDEO in this app.
The 300-6 was one of the best Ford engines ever made. The only way you can really hurt them is to run them out of oil. I just sold my 1990 F250 with 300-6 with 249,000 miles. It used about 1 quart every 500 miles. The truck was a Cokacola truck so i am sure it was abused heavly. I would just head to walmart and buy some Havoline or even supertech for that matter. Either way the truck life is only about half gone.
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