Oil selection (10/2009)

[bobcowan]

Shell Rotella was used by diesel engines for quite a while. It was a CI-4 oil, and had lots of ZDDP. That was good for diesels, because a lot of them still use flat tappets. The '07 Cummins in my truck has flat tappets. Also, diesel's didn't have cats. The whole point of removing the zinc was to protect the cats.

That made oils like Shell Rotella very attractive to older engines. I used it in my '66 Mustang up until I sold it just for that reason.

Fast foreward to 2009. Many diesels now have a cat. Shell Rotella is now a CJ-4 oil, and has cut it's zinc content by 25%. It's slightly better than standard oils, like M1. But not the panacea it used to be.

If you want the additional ZDDP for engine wear, you'll have to use an additive from GM or Comp Cams. I have heard that STP oil treatment adds a huge dose of zinc. But I have not been able to prove it.

My car has an accumulater. I added it after spinning a rod bearing on the track one day. I use the Canton Accusump, 2qt. I didn't have room for the three qt. It's mounted in the engine bay, just in front of the engine.

I have seen race only cars with the Accusump mounted in the trunk. It's out of the way, protected from damage and heat, and helps balance the weight. The hose is longer, but that doesn't really matter. That just means a longer column of oil, but it will still move back and forth according to the pressure at the head of the column.

I'v also seen dry sump tanks mounted in the back for the same reasons.