I have a 2001 Mercedes C240 with manual transmission. Yesterday, I changed the oil and oil filter. I used regular 10-40W oil. I noted on the web that I probably should have used synthetic oil. Is it a must to use synthetic oil for this vehicle? What if one does use regular oil, any harm?

By the way, it is so easy to change the oil filter but it is a pain to change the oil. You have to remove 8 hex nut screws (need 8mm socket), drop two plastic under covers, and unscrew the drain plug (needs 13mm socket).

 

Which is why Mercedes Benz doesn't do the oil change from the bottom of the car. They stick a tube down the tube that leads to the oil pan and suck the old oil out, eliminating time and labor, and therefore cost. I has been argued over and over whether this is as effective as the old "pull the drain plug" method, so I won't get into that argument, but myself.......I still do it the old fashioned way. Maybe it's just me.

As far as the oil itself goes, here's another one that's been hashed and re-hashed for years.
The car came with synthetic for a reason....and there are a few. I use the factory fill Mobil 1 synthetic only in mine when I do it. The weight is up to you, but I use 10-30 from Costco which is the best place I've found to buy it by the case and save a little bit. I buy the filters online a few at a time. No tax, no shipping.

Oh yeah, my car is an '05 with 157,000 miles on it and running great.
33.5mpg on the freeway at 65mph. Not bad.

PS> a lot of you will say to use the 0 weight oil. That's fine. Climate dictates what you use and I think the 0 weight or the 10 weight oils are fine for just about anything.

 

When you say depends on climate, do you mean 10 is for bad conditions and 0 is for regular conditions? I live in Hawaii, I want to know if I tell the oil change place 0 or 10? I thought they would know what kind of oil, but they said I need to look under the hood on the cap and it will tell me. But it doesn't. Thanks for your help.