True, enough, Doug. But we have no evidence here that the OP is abusing the engine is such a manner with the engine brake. And we have no evidence that overhead adjustments are not being regularly done. But since all commercial heavy diesels are equipped with engine brakes in the U.S., it would show a similar pattern as the OP is having, if engine brakes are the primary issue. Since most commercial trucks are operated by mechanically ignorant folks, many of whom could give a rip about how an engine is treated since they don't pay the bills in relation to operating it, we should see a industry wide pattern of engine brakes causing issues. We don't. And the vast majority of commercial heavy diesels in N. America are using a mineral based 15w40 CJ-4 oil in them.
The source of the problem could be as you suggest, but the odds are against it. I can't speak in regards to how they do things down under, but while fleets and OEM's make recommendations regarding operation of heavy trucks here, in reality, things that actually occur are quite different. After 40 years of watching these morons operating commercial trucks, I can attest that many drivers have little regard to the things we are discussing. While telematics is making inroads into watching driver performance in operating commercial trucks, no one is watching engine brake applications. That is, except the local LEO who tries to catch commercial trucks using an engine brake in a restricted area so that he can generate some more revenue for the city or county.
The source of the problem could be as you suggest, but the odds are against it. I can't speak in regards to how they do things down under, but while fleets and OEM's make recommendations regarding operation of heavy trucks here, in reality, things that actually occur are quite different. After 40 years of watching these morons operating commercial trucks, I can attest that many drivers have little regard to the things we are discussing. While telematics is making inroads into watching driver performance in operating commercial trucks, no one is watching engine brake applications. That is, except the local LEO who tries to catch commercial trucks using an engine brake in a restricted area so that he can generate some more revenue for the city or county.