Re: Engine oil

Posted by Tim Cole On 2008/2/8 21:26:25

Hi! It's me again (Tim Cole) the oil change guy.

I have some Packard manuals in front of me. In 1954 and 1955 they list three grades of motor oil: ML, MM, and MS. ML is Regular motor oil, MM is Premium motor oil, and MS is Detergent motor oil.

In 1954 the Packard Manual specifies either ML or MM but not MS. That is, for the straight eight use non-detergent.

In 1955 the Packard Manual specifies MS Detergent for severe service in the V-8.

Why has this changed?

The answer is that the V-8 has a Full Flow oil filter whereas the straight eight has a By-Pass oil filter.

In a detergent motor oil contaminants are kept in suspension so that they can be captured by the full flow oil filter. They never get to the bearings.

With non-detergent oil contaminants "settle out" into the oil pan when the engine is shut off. Over time this becomes visible as sludge. That is your primary filter.

Without a full flow filter detergent oil is actually detrimental once contaminants build up to a certain level because they impregnate bearings and gears and cause corrosion.

The 34 through 39 senior Packards all had full flow filters and so they can use detergent although the V-12 seems to me to run quieter on non-detergent.

The 2000 mile service interval (1000 for severe service) is designed for non-detergent oil. The problem is that using detergent is considered severe usage without a full flow filter.

The primary reason modern cars can go 7500 to 10000 miles without oil changes is not because crude oil has improved, but because the engines run so much cleaner. Those carburetors are really dirty especially with old fashioned air filters. The modern oil additive packages accommodate these longer oil change intervals which also causes less waste.

Now when it comes to beating the daylights out of Packards fortunately a lot of Packard speedometers read too high which helps the engine. Other than the V-8 the little 288 is probably the most rugged plant because of the shorter stroke. The solid tappets are also a better deal. However the larger 327 with its 4 1/4 inch stroke is closing in on the old super 8 and the 359 is only 1/2 inch behind. A 1954 Patrician is churning 3000 rpm at 65 mph which is pretty substantial. It sounds pretty busy at 55!

If you don't believe me take a stick shift 327 to the drag strip. After you have been pushing it higher and higher to improve your time you may encounter a gigantic boom when number 2 connecting rod goes into orbit. For some reason the rods like to fly out in one piece leaving the piston inside the engine. When you pull over the motor will probably still be running albeit with a miss.

That's why I don't push Packards. An M-80 is a lot cheaper thrill.