Oil question?

[fordcoupe]

Originally Posted by Joe K

The original Model A engine was designed for non-detergent oil. The theory then was that oil was (besides being lubricant) transfer medium of wear products to the bottom of the oil sump - which would be periodically cleaned out as the crankshaft main bearings adjustment was done.

Non detergent oil will allow wear products to "settle" out.

The development of detergent oil was parallel to development of pressurized oil systems. Instead of the quiescent oil dropping the wear products, detergent oil/pressure systems were designed to keep the wear products in suspension so they could be removed by oil filters which were part of a pressure lubrication system.

A non-detergent/oil pan settle system as in the Model A had an oil change frequency of 500 miles. A detergent/filter system as in modern cars had an oil change frequency of 2000 miles (back before the 1960s) and with the improvement in oils and filters, this has been brought to 7500 miles.

So each system type has their "envelope of operation" and where they are operated best.

It's hard to say which is truly best: non-detergent systems get nice "clean" oil every 500 miles - but they waste a lot of oil in changes. Detergent systems use the same oil over and over (and how effective is filtering - it can't be 100 percent) but are conserving of oil. And the Model A stock engine ain't designed for detergent oil and HAS NO FILTER.

I myself use a detergent oil - but change the oil every 500 miles - well maybe 750 because I'm lazy - and the oils today ARE better than they were in 1930.

So maybe I get the best of both worlds? Or maybe the worst?

A recent discovery of mine while I worked at the farm repairing diesel tractors is that the old fashioned SAE30 non-detergent oil is now quite a pricey commodity. About double the cost of detergent SAE30 oil. One of the tractors used 15 gallons of non-detergent oil - the farm owner insisted it stay on non-detergent as the same oil was used in the hydraulic systems - which did not have their own filters (although the engine did - go figure? This a British tractor IIRC - Pain in the butt to fix.)

Detergent oil does keep all those "other" areas of the engine internals cleaner. Dipper tray, valve chamber, even engine internal surfaces. And modern detergent oil is perhaps made more "consistent" as it has a whole bunch of SAE group numbers (specifications) to govern performance that the non-detergent does not get.

Modern detergent oil may have other advantages. I am frankly SURPRISED at the amount of black wear products that a change of synthetic oil DOES NOT have. That stuff must be teflon on ice. Although I have not broken down an engine using synthetic oil - everything I read on this indicates that synthetic oil leaves the engine internals MUCH cleaner than anything else - primarily by reducing wear and wear products.

And for engines - cleaner is better.

You will probably NOT trash your engine using non-detergent oil as some have opined. Still, I can't say that a detergent oil has any real advantage EXCEPT for the lack of oil contamination/wear that a synthetic detergent oil seems to have?

I may start using a synthetic detergent oil - I might have to extend the change interval out to maybe 2K miles?

Well, the stuff is EXPENSIVE...

Joe K

Good information thank you for sharing

[Joe K]

And not mentioned but relevant is that even common everyday detergent motor oil has a certain percentage of synthetic oil.

My VW Golf Diesel requires synthetic oil - this primarily due to the turbo attached to the engine - which is slaved to the engine oil supply.

I say required - VW does give lubrication requirement and intervals for "mixed blend" oil - oil containing both synthetic and non-synthetic feedstocks. And gives the SAE groups allowed.

Look up the SAE group numbers for these allowed mixed blend oils - it turns out that you can't buy a non-allowed oil in the store - EVERY oil on the store shelves meets the SAE group numbers - meaning every oil contains SOME synthetic component.

We keep saying that oils have improved - Here is proof - and the reason why.

A synthetic revolution is what it is.

Joe K

[warren va]

Thanks everyone for your replies. I will definitely go with the detergent oil.

Warren