1. 10w40 regular oil should be REMOVED ASAP from the engine, that is not a diesel oil and has nothing in it to help trap soot particles and cannot stand the higher pressures in a diesel, it will increase wear on the engine

2. 1-1.5 bar after a hot highway drive is normal, as long as it pegs back up to 3 at anything above 1200-1300rpm.

3. Valve guide seals are not a common maintenance issue for this engine, most never need it, and they have nothing to do with your oil pressure.

4. More likely your problem is due to the gas engine oil you are running, it may be breaking down. CHANGE IT with diesel oil! I'd use a 5w40 synthetic DIESEL oil of your choice.

Hopefully this helps. I'd get that gasser oil out of there right away though.

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