For older engines, that do not have roller cams and such, I think it is important to note that new formulated oils with the SN rating, have significantly less Zddp in the oil. Zddp, has for a long time, been an additive in oil, the purpose of which is to give Ferrous Metals, while under heavy pressure, extra protection.
The reason why we see less Zddp in oil today (compared to previous oils rated ...SJ,SK,SL,SM) is that Zddp has been known to reduce the life of Catalytic converters. Generally speaking, the auto industry has been wanting to expand the life of Cat's because they have been federally mandated to warranty them for longer. The only way to extend the life of a Cat is to reduce the Zddp that flows through it. Sadly, it is at the expense of the innards of many engines.
Some folks are using oils for Diesels, like Shell Rotella 10W30 or Valvoline Fleet plus 10w30 that has higher Zddp levels than on conventional motor oils found on the shelves of many retailers. It works!
Another option is to purchase a Zddp additive, such as Lucas Oil - Engine Break in Additive.
http://www.lucasoil.ca/products/product.asp?id=67&cat=AutomotiveI use this product on my TJ, but only add in 40z. per with the 6 litres of Valvoline 10W30 (white bottle). Any slight lifter noise that my TJ has had, is long gone.
I o not recommend using the whole bottle (16 oz.) in your engine. You just want to boost the Zddp levels in your oil to protect your engine. Eventually it will be at the death of my Cat's but I figure it is cheaper to replace the Cat's than rebuild my 4.0L engine.
BJ
Topic: 4.0 L engines seizing (Read 2534 times)