What are the users of OLD IRON running in their diesels? I use diesel engine oil of the 15W-40 flavor. I have used Chevron Delo 400, Castrol Tection, Shell Rotella T, and Motorcraft. Surely this is an improvement over the old oils of 1962.

The reason I ask it I read a recent post about "low ash" oil and I assume it was for gasoline and LPG tractors... I did not hear anyone mention diesels but read a few use 15W-40 in their gas tractors.

Charles

Charles: I use 15W-40 in everything, diesel tractors, gas tractors, gas and diesel cars and trucks, even my 4 cycle lawn mower. The mower is a 1975 model, given to me when I bought my 1066 new. The engine is the only item original.

Never rebuilt a diesel under 10,000 hours, only one gas tractor under 4,000 hours. Put 300,000 mile plus on numerous V8 GM gassers. Currently have a V6 Buick over 200,000 miles. The first diesel I ever used 15W-40 in was my 560 with 282, just two more cylinders of your D-188.

Good deal! I have been using the 15W-40 for years in diesels, but did not know if it was too heavy for auto use. I am currently using it in my 18 hp Briggs on a Snapper mower. Do the brands matter? I have been tempted to use the Wal-Mart brand "Super Tech", $11 US a gallon.

Charles

I've been useing Walmart Super Tech 15W40 for years.No problem yet?

The reason IH came out with a low ash for gasoline is that they were trying to get a long life oil to use in all their engines. They found that they needed two different types of oil to make things work. When they added more ash content the spark ignition engines developed many more valve problems. Failures in 300 to 700 hours on test engines.

Sulfur in the diesel fuel when mixed with water becomes sulfuric acid. The ash in the oil neutralizes that acid. To get to a hundred hour oil change interval they increased the ash content. This is why you should not use a low ash oil in your diesels, though with the low sulfur fuels the need for the higher ash content is greatly lessened.

The increased ash content caused problems with the newer gasoline engines by leaving carbon deposits on the exhaust valve stems. This doesn't cause much of a problem for an engine that is run under a uniform load. The problem comes when an engine is run with a partial load and then fully loaded or overloaded. The increased load raises the temperature of the valves and the increases temperature causes the valve stems to expand. The valve stems with the carbon deposits on them no longer have enough clearance and they will hang open instead of fully closing. The hot combustion gases passing by the partially open valve will burn it out just like using a cutting torch on it. When it happens it is very rapid, only a few revolutions of the engine. It was very common to see this type of failure in the spring and fall as these tractors went from light duty to heavy tillage. Using low ash oils will greatly reduce this type of failure on these engines.

After I found out that the diesel truck oils no longer have the zinc and phosforus additives needed for flat tappet cams and lifters(most old iron) ,I started useing the Case IH brand 15/40. Only about a buck more a gallon than Rotella and I'm supporting a small town IH dealer that has been very good to me about getting parts over the years.Definetly cranks faster and picks up oil pressure in cold weather.