What the hell happened?
 

I get my oil changed yesterday and they put 10W-30 in instead of what i usually use (10W-40) And all the sudden i have this rattling noise when i start off. It sounds like it's coming from the valve train. I suspect i may need to adjust my valve lifters has anyone ever had this?

adamdaviddoyle,
If the noise only happens at startup I'd look into adjusting the valves. However, I've been able to eliminate that noise by using a different oil. You mentioned the viscosity you normally use but not the brand. I've found that an oil with a higher ppm of molybdenum will quiet things down...something like Pennzoil High Mileage will do the trick. Or, if you want to spend the money, RedLine.
Bogatyr

I normally use the "high mileage" brand... but i hadn't changed my oil in about 5k miles.... so i ran out at lunch and just got the service center to do it for me. and they used the lighter weight... (Cheap) oil i'm sure. I'll probably adjust the valve clearance this weekend and change the oil myself.

Thank you for the reply... i was hoping i was barking up the right tree :)

yah lower viscosity oil will cause more engine noise cuz there isnt as much lube on ur moving parts, or as much resistant lube if that makes sense