Engine oil for 1972 Mark IV 460 cui

[Lincoln1967]

Which oil should I choose?

I am thinking a 15w-40 or 10w-30 will do? Mineral or synthethic?

The car will mostly drive in temperatures between 55F-80F.

[papawayne]

God bless 55-to-80-degree temps. Not bad. The last time I changed the oil I used 15-40 with zdpd or whatever those initials are. My brother suggested it, but Prompto oil change stuff always worked for me, too. Cheaper and who knows? Wayne

[Dan Szwarc]

Whatever you do, read this thread:


New oils are ruining our cars.
viewtopic.php?t=18359

[TonyC]

Oil weight does have its effects. 15w is too thick for that engine. It was built for 10w-30 or -40, so stick with that. I'm not going to harbor an opinion on natural-vs.-synthetic, to avoid a war with any advocates for one or the other. I personally stick with the natural, or a blend.

But you must always include a $12 bottle of ZDDP with every oil change. The innards of your engine require zinc-phosphate to prevent friction damage, and new oils do not have that ingredient now (the main reason behind the link Dan shared). At least there is that 6-kilomile oil-change interval the engine was built for, so your maintenance costs are checked by not having to do oil changes every other week.

---Tony

[1Bad55Chevy]

Oil weight does have its effects. 15w is too thick for that engine. It was built for 10w-30 or -40, so stick with that. I'm not going to harbor an opinion on natural-vs.-synthetic, to avoid a war with any advocates for one or the other. I personally stick with the natural, or a blend.

But you must always include a $12 bottle of ZDDP with every oil change. The innards of your engine require zinc-phosphate to prevent friction damage, and new oils do not have that ingredient now (the main reason behind the link Dan shared). At least there is that 6-kilomile oil-change interval the engine was built for, so your maintenance costs are checked by not having to do oil changes every other week.

---Tony

Isn't the W in 10w-30 for 0 degrees and below?

I have always ran multi weight oils but I have been starting to second guess it for my classics.. thinking about switching to just 30, 40, or 50wt oils.

[Dan Szwarc]

Oil viscosity explained.

https://www.castrol.com/en_us/united-st ... ained.html

[TonyC]

Short answer, yes–"W" indicates the winter weight. Sorry I didn't clarify that earlier.

---Tony

[1Bad55Chevy]

I understand it stands for winter but I thought that ultimately meant below 0 (maybe below freezing). The Castrol article never outlined what temperature the oil had to be to perform as a lighter weight. Maybe different brands have different specs because I couldn't find a clear answer for that online but I didn't look that hard.

[Lee]

Regular straight grade oils are tested at 212F, and are classed based upon their tested viscosity at that temperature. If an oil has a W designation, it must be thinner than a stated viscosity at various low temperatures depending upon the grade.

[TonyC]

Very good reference there, which helps to explain the W side of multi-viscosity oils. My Reader's Digest Car Care Manual also got into that explanation in detail; but I cannot yet scan any hardcopy pages, as I haven't yet installed the new printer I bought a couple months ago.

---Tony