I have forgotten most of what I learned about lubrication tech when in school, and in the shipbuilding industry and later automotive industry, where I mainly worked on heavy military equipment design and testing. But, I do remember the engines in the old days, when I took them apart. They were totally clogged with carbon debris, left from the oil breaking down. And, with the two major types of crude, the asphalt from Tx and the wax from Pa, the so called blends were enhanced to accommodate the higher output engines. What we found is that our modern auto engines no longer spew a trail of smoke as we drive. When kids, the air was always full of a smell of carbon thru traffic....no longer. No huge smoke from the diesels, due to very high injection pressures and turbos for the most part. No wear on the inside of engines as we used to find after 100k miles with a huge ring ridge. But, the geniuses found that the zinc and phosphorus in the oil would kill the cats, so, you began to find a star on the outside of the oil spec marker on the bottle, and with that was the reduced additive. This is based on an ASTM API four ball test, with lots of pressure and not hydro film generation as on normal film bearings. And, since the diesels had no cats back then, they kept the additives, and are better even now. I have used diesel trucks and tractors for decades and find a couple things. First, how serious a problem is it....say for a lawn and garden type flat tappet engine using this new oil.....hmmm....not too shabby. Also, they then changed the engine coolant to remove the additives that prevent cavitation and sleeve destruction. And when that happened, a lot of wet sleeve diesels bit the dust....cav resulted in loss of seal on the sleeves and coolant loss. And they changed the fuel, and removed the lead......cat again. Did this tend to cause valve recession.....yep. Big issue, maybe not. But, I like to err on the side of caution, since I no longer can afford or enjoy the destruction of my mechanical stuff. So this means making sure you use the correct coolant esp in engines with wet sleeves. I have always added the ZDDP in those engines that had flat tappets OR that had a lot of chains, esp driving cams. And note that almost all overhead cams fit that size shoe.....they aint got no stinking rollers. And, I like to use fuel additives where appropriate. This is also true for my diesels that no longer have the sulphur to protect the pumps.....and guess what happens. Even in the last decade, the geniuses at GM have ruined the fuel pumps on the japanese Isuzu engines that are called duramax......right. They eat their fuel pumps due to lack of lube.....I think they are CP4 pumps.....I have one. So, this means add a lift pump and use fuel with added sulphur.....and oh by the way, Southern States does that for you as well as brings up the cetane....very nice. It is called preventative maintenance......and I also will bleed my brakes to remove the great hygroscopic fluid that collects water, and turns brown, then black. What color is your brake fluid.
