I have a motor repair shop and find that straight SAE 40 oil works wonders for minimising leaks and reducing engine noise on older vehicles. Bear in mind that i am in South Africa so low temperatures are not an issue .On one of my personal vehicles ,Mazda 323, B3 engine i found that using 20W50 and `15w40 oils would have the dipstick showing on the min level every two weeks ,this started happening when the car reached 200 000km .Started using Magnatec 10w40 and this has stopped ,oil consumption over 5000km is now minimal, not even showing on the dipstick .
How is this possible ?
The Mazda B3 engine was designed in the eighties and only calls for a basic 20w50 multigrade oil .Magnatec is Champagne to that motor! Any views as to why the sudden improvement in oil consumption ?