Alternative Oil?

[ipsos95]

Hello everyone, First post so be gentle!

My car is a Renault Megane estate 54 plate, for the last year my car has been drinking oil (to the extent of 5 litres every 6 weeks). I do drive about 500 miles a week for work and there is 150,000 on the clock. My garage says it's just because of the age of the car and the mileage i do but it used to go from service to service without a top up. The oil i'm supposed to use is 5w/40 which is apparently a thin oil and will burn up quicker. I was told by someone that because my car is old and has high mileage i could use a different/cheaper oil, would this be true?

thanks in advance for any suggestions.

[Mave]

If you're burning a litre every 600 miles then its not due ot the oil viscocity. Something else is causing the problem.
Not sure if they're still doing it, but Halfords were doing a deal 5L for £10 for various grades; might be worth getting a load if you can.