tywebb1967 said:
Many informed people without avested interest think that 5W20 and even 5W30 should never be used except during winter in cold climates. They feel sthese oils have too many viscosity improving additives which form varnish-like deposits over time.
So what would you use then ???
Tricky question. A person should really do their homework on the model car they have - join an owner's forum and compare opinions form people who've seen and understood the schematics & taken the engines apart and are in a position to understand if in fact there are spots in the engine where it is trully necessary to use an oil lighter than 10W30 to get a drizzle of lubrication through.
My car is a spec'd for 5w30. I've been running it with 2L of 5W30 and 2L of 10W30 while keeping a bottle of 10W40 for the 1/3 litre top-offs between oil changes. If I decide to keep the car past this summer, I will probably switch to Mobil1 10W30
(which most experts think flows as well as conventional 5W30,) though I might mix in a litre of 5W20 syn during the three coldest months of the year.
The original point was that there is probably no car on the market that actually needs 5W20 as opposed to 5W30, and most would probably be better of with 10W30 synthetic.
