[Erwin]

I have a 48 ford f2 pickup with a flathead V8 and Im changing oil finially, i am going with straight 30w.but the auto parts clerk said be careful because those "old" trucks use to take non detergent oil. I s detegent oil safe to put in or not? thank you!

[MochetVelo]

There are a lot of threads on this subject, and several articles in Skinned Knuckes and other publications. The general conclusions are 'use the newer detergent oils'. They will keep your engine cleaner. You might want to drop the oil pan and scrape it out first, though!

Phil

[StrombergEE3]

It is so sad that the advertising folks for the petrol. industry had such little confidence in the American consumer, that they came up such nonsensical terms. Here's the simple technical facts.

There is no such thing as "detergent" oil.
That term was used in the hopes that people would understand that "detergent" oil prevents engines from "coking up" with sludge. "detergent oil" HAS NO DETERGENT IN IT. IT NEVER DID. IT CANT. IT NEVER WILL ! What it DOES have is the ability NOT TO LINK UP CARBON PARTICLES. They stay in "suspension" so they can be filtered out.

In the 1950's, I did a little experiment to prove to my disbelieving friends what "detergent" oil can do, and what it cannot. When I when thru the engine on my 1930's "collector car", I deliberately left one "pocket" of sludge in a corner of the inside of the engine block.

As a matter of good engine protection, I "drop" my oil pan every couple of years - those old long engine pans dont drain that well - since most "collector" engines do not have "floating" oil pick-ups, they suck oil up from the lowest portion of the oil pan.

You guessed it - it is now some SIXTY YEARS LATER, and those of my doubting buddies who are still with us, get to have the simple fact rubbed in their noses, that "detergent" oil can not and will not "dissolve sludge".

multi grade oils
The term "multi grade" SHOULD apply to so called "standard" (as in cheapo) single viscosity oils. Why ? Because they are not stable ! For example, a single grade 30 will be 30 weight oil at 210 degrees. But your actual oil operating temp. may be hotter or colder. A single grade oil can "THIN OUT" at high temps. It can turn to a goo at low temps. Either way, the use of single grade oil is a good way to reproduce the short engine life we accepted prior to the introduction of modern oil chemistry.

The oil industry, again, not having any confidence in us consumers, came up with the term "multi-grade" to mean oils that will be thin enough to provide safe starting when it is cold, but do NOT thin out as they get hot.

So - there you are - simple facts. I suggest you LISTEN to the poster above who recommends "pulling" the oil pan, and do that at REGULAR intervals of at least every two years on any older "collector" car. I suggest you FORGET what the back-yard wrench turners tell you, unless they show you copies of their engineering degrees, along with the attachment that shows you they specialized in petroleum engineering...!

The term "multi-grade" oil is "upside down" with the facts.