driversdomainuk 8 Posted July 15, 2008 Hi Before I have to do a full rebuild on my Mi due to low oil pressure I want to check a few things. I have fitted a mechanical oil pressure gauge and warning light, and yes the oil pressure is low – idles when hot a around 10psi, although hit over 100psi when revving at cold thanks to a comp oil pump. I am wondering if the oil I am using is the problem – it is Shell Fully Synthetic 5w 40 (should be using 10w 40) do you think I may be lucky, and by going back to 10w 40 semi will solve the problem or is this quoted oil pressure too low for an oil based issue..? Cheers Share this post Link to post Share on other sites
CaptainK 11 Posted July 15, 2008 If my knowledge of oil is correct then a 5w40 and a 10e40 are the same viscosity at "hot" temperatures. The first number - 5w or 10w determines the viscosity when the oil is cold, and the last number relates to the hot viscosity. As both oils you mentioned are "??w40", giving a "40" hot temperature then there should be no difference when at running temperature. I run Silkolene Pro S 5w40 in my GTi6 engine and my FTO as I prefer the better cold start protection offered by a thinner "cold" oil at engine startup. Share this post Link to post Share on other sites
