20W50 oil vs. other oils

[ClareQuilty]

For a while now I've noticed that my mechanic shop puts 20W50 oil in my 30 year old Corolla, which is I think a somewhat unusual grade or weight of oil. I remember back in the USA they usually used 10W30 or something like this. I asked the mechanic about it and he said that a 'heavier' grade of oil was appropriate for such an old engine.

Can anyone comment if he's following a good policy here? I do find that there is a very long period of valve clatter (and oil light) when the engine is first started up in the morning.

[transam]

The oil is probably correct for the age of car. Most engines make a noise until pressurised oil has reached all parts. Don't put a thinner grade oil in.If it runs OK and your oil light stays out when warm and at idle then all is OK.

[WarpSpeed]

Yes he is, and quite frankly it's surprising to hear..