The Mobil 1 oil I normally use here in the UK is SAE 5W 50, however, yest= erday when I went to buy some, I was told it had been replaced with Mobil= 1 Tri-synthetic performance oil which is 0W 40! I am concered that for owners of high mileage cars, good synthetic oils a= re becoming to light and runny to offer the protection which allowed them= to become high mileage in the first place.