Interesting white hat as I am about to go to 10w40....So what oil do you think is too thick on a 112k engine with piston slap ( sometime hot sometimes not slap at all)

 

Pistnbroke -- i would go with what Zray is using, the European formula if i remember correctly. I use something very similar.

Here is a crazy thing to note. When i first had some mileage on the car, i asked a trusted tech to listen through a cold start and warm-up. He said everything is normal. I use this as my baseline. The sound which some call "slap" goes away in a few minutes depending upon how cold it was at start. I treat all engines this way, essentially getting to know them and expectations. Why do i do this? Because some people are more sensitive to certain sound frequencies. My friend worked with air tools his whole life and the audiologist knew this exactly without knowing anything about him. She also called me for having been closely exposed to an explosion. the result does not affect every perception, just certain frequencies. Thusly, something might sound "worse" to someone than another as the perceptual system has adapted. With certain losses, some things are MORE pronounced. The takeaway here is to have someone familiar with these engines as an objective third party tell you if there is really a problem. Probably not, or else there would be other massive signs.

Remember that it is essentially a solid cam under plastic valve covers, an Aluminum block and heads with steel internals. It is going to make some noise, and with Jaguar's excellent dampening of all other sounds, including the white noise of intake (yes, that sound can create this effect in other engine setups.), we are hearing the one thing which cannot be concealed which would otherwise be drowned out with other installations. Hope that this helps.