Is "motor oil's motor oil"?

[coffee break]

It's happened twice today and on more than one occasion before. I'm out running errands and I'm wearing a Sebring t-shirt which has "Mobil 1" on it. Someone will stop me and they have been using Mobil oils for yearssssssssss.

Today I was looking for diesel motor oil as suggested in another thread and the parts guy was telling me it's the oil to use.

I figure, if I make sure the level is good and change it as suggested, that should be good enough.

So, is motor oil just motor oil?

Edited September 22, 2016 by coffee break
motor oil

[Ian7]

Other than looking similar to each other to a layman, there are MANY critical functional differences between motor oils depending on their intended application.

[oilteq]

Many years ago, Ford tore apart some catalytic converters, analyzed the glass-like material on the surfaces, and found phosphorus. The industry tried to develop an engine test to determine an oil’s propensity for building cat deposits, but could not get repeatability. So, after wasting a few hundred thousand dollars, they put in a physical limit of 1200 ppm. A few years later it was lowered to 1000 ppm. Then they lowered it again with the API SM spec to 800 ppm.

 

Phosphorus comes from ZDDP, a zinc phosphate anti-wear additive. Although phosphorus is what is limited, zinc is what the market recognizes. Google zinc and cam failure and see how many hits you get.

 

New engines have lower valve spring pressures and are not a problem. Older flat tappet cam engines do not last as long on current passenger car oils. High RPM increases load between the cam and lifter. Performance cams ramp up faster and increase load. Diesel engine oil is allowed up to 1200 ppm phosphorus (API CJ-4). Racing oils are not limited and often warn against use in passenger cars.

 

For most Se7en owners, I recommend a diesel engine oil that also meets gasoline engine requirements (API CJ-4/SN). Due to a quirk in the rules, if the diesel spec comes first, they waive the gasoline engine phosphorus requirement. It should be readily available in SAE 10W-30 and 15W-40.

 

Blaine

[NVP66S]

I was working with Roush Engineering a few years ago (I was their customer on a development program). One of the engineers there that I respect told me there are huge differences between the good stuff and the cheap stuff. He recommended either going to the dealer for oil changes or using Mobil 1.

 

Also on a more personal note, when I was a young squirt I started my driving career using what my father used: Quaker State oil. This lasted several years. I had a POS 1976 Honda CVCC that burned oil and left varnish on the inside of the valve cover, etc. It got steadily worse until it only got 200 miles per quart. I switched to Castrol GTX and the consumption went to 600 miles/quart and the varnish disappeared. This was ~1986. (That car had problems that you only see in Hollywood movies)