I have no problem putting in a heavy oil to save money. I know the EPA in the USA wants thinner oils. Has anyone notice a diffrence in mpg?
It wouldn't matter (MPG), use what you have and be happy that you still have it. Depending on the local temps, you should be safe in using a thicker stock.
Australian owner's manuals are similar, show a wide range of oil weights. The north american manuals get a little hilarious: 4th gen for example, saying to use 0W16, and if (god forbid) 0W20 is used, replace at the severe service interval, with 0W16 .
I used Shell Rotella 40W (straight) for my first 15000 miles with my used Gen2. And, then used Shell Rotella 15W-40W for the next 50000 miles of life with my Gen2. Shell Rotella is an oil for diesel engines primarily. I choose it because Shell Rotella has tons of detergent. Only thing I noticed with the straight 40W and 15W-40W was that I was getting a bit of rattle from the valve cover when starting up in cold weather (say, below 35F). Best guess is that the rattle is caused by the VVT mechanism when cold. PS I purchased my used Gen2 at about 200k miles. PPS My oil burning and blow-by situation has improved so much since starting the Shell Rotella. So much so that I decided to see if oil burning (and blow by) improvements are still obtainable WITHOUT the Shell Rotella. Last oil and filter change I used 3.5 quarts of Walmart full synthetic Supertech 10W30. Four thousand miles since last oil change and I have consumed 1/2 quart of oil. With a substantial portion of oil consumed being captured in the after market oil water separator.
I just did an experiment with diesel oil in my van (chrysler 3.8L) . So far so good. I used 5w40 diesel Oil full synthetic. Some people say it can possibly damage the converter because of the higher ZZDP but its very rare. I am going to put the diesel oil in my prius the next oil change. I used it before, and it did very well! Did not smoke as much and burned way less oil. Your high millage used is proof it works I had the rings get stuck before so high detergents definatly help prevent that. I don’t think it would be good idea to add the Engine Restore additive with 15w40. What do you think? I am unsure if it will make it too thick like Lucas. Did you notice a significant difference in fuel economy in your experiment? I do have a lot of blow by I am going to make a post soon. The owners manual states adding 1.1qt per 600 miles for the 2nd gen is normal. Thats very high IMO.