Hello- Well I have this question. My late 1970s Volvo MD11C (two cyl) is hard starting especially in cold weather (cold weather being relative in Florida e.g. low 60 degree F). The engine has no glow plugs or other way of preheating. After reading up on oil viscosity I am wondering if the fact that I have been using a straight 40 weight Rotella-T diesel oil could have something to do with it. I think I changed to that after someone recommened it. The technical data in the back of the owners manual says straight 20 weight volvo CD diesel oil which I cannot readily find. What I am wondering is could I use the Rotella-T 15W-40 weight oil now that I understand that multigrade is meant to be 15W (thinner) when cold and 40 (thicker) when hot. Does it make sense that this might make the engine easier to start but still provide the wear protection when the engine is warm? Be kind..."I'm blonde"
Carole in Florida
Carole in Florida