I've been using it because I've had really good luck with the stuff in my 318 and 4.0, never had any kind of serious failure in those.
I don't rock crawl, a few easy trails a couple of times a year to go fishing or launch kayaks. Cruise just below 18,000 RPMs, shifting around 22,000 RPMs. I do all my own maintenance, it's only been in the shop for tires, so it's not like a tech is lieing about work done.
Umm, my math for Marines tells me that 2 x 1000 = 2,000 not 20,000 RPMs.
Personally, I think you're cruising and shifting at too low an RPM for this high revving truck.
Like you, I have the manual transmission. When cruising I prefer to stay in the low end of power band at about 2,500 RPMs for a better response between gas mileage and a need to accelerate because of the distracted idiots out there on the road.
I don't shift until at least 3,000 RPMs when I shift accelerating slowly.
Here in Missouri, the speed limit signs on the highways are 65 MPH around me but most on the road are doing a good 10 MPH over that. So getting on the highway I'm usually not shifting until 3,500 RPM or higher.
Remember that the shift tables in the owners manual are specifically designed only for the very best MPG due to the Corporate Average Fuel Economy [CAFE] requirements for the manufacturers. They have no basis at all in real world driving.
If you really are shifting at 2200 RPM and cruising at 1800 RPM you would have obvious lugging on any carb fueled engine with a RPM redline at 6,500 RPMs.
The fuel injection prevents the shuddering effect but the very simple test that you're still lugging the engine by being in a higher gear than you should is that you have pretty much zero acceleration without downshifting first when you press the accelerator. If you're doing this you are increasing the heat of the pistons and cylinder walls and it will ultimately cause engine issues.
That said I don't know that it would affect the cam and rocker arms.
‘This confuses me. Seeing a few of your replies I sense you probably have some good real world experience but your opinion of Royal Purple goes against the grain of what the BMW crowd swear by and that’s where I was introduced to it. I’ve run it now for at least 20 years in BMW & Porsches with no engine issues of any kind. Several of these cars were dyno’d between 350-450 hp and tracked regularly. I’d send some oil out for testing about once a year and the report would always show that the oil was still in great shape.
