I'm scheduled for my 7500 service and would like to start using a synthetic oil. My service department offers Castrol Syntec as their synthetic option. I asked this board about that brand and the majority of responses were negative. The service department will use any oil that I supply them with. So, what is the best synthetic to use? I've seen a few posts praising Amsoil as the best. Any opinions on this brand? Be specific in recommendations as I've found that there are different grades of many of the synthetics, ie. 0W-30w, 5w-50w, etc. I've got 2 weeks before the service appointment which is plenty of time to find what I eventually select and have it delivered if mail order is used.

Thanks all.

I run Mobil 1 10-30 as per the manual. I have the turbo and the manual calls for synthetic AND drain intervals of 5k. Given that, the price of Mobil 1 is better than Amsoil.

I also run Mobil 1 at 7,500 intervals on my wife's C280.

I've spoken to MANY mercedes mechanics who use Mobil 1 over long lives of their older benzes (300k) and after they take the engine apart for a valve job, they say the results are great.

Just stay away from Syntec 5w50. Lots of additives in there to give that big a spread (5-50). They break down earlier than the oil.

Another vote for AMSOIL 0W-30. Running it in 2 Saab turbos and a Volvo turbo. Will cost you about $2 per quart more than AMSOIL 5W-30 or 10W-30, but it is a better oil (and may give better fuel economy--does so in most cases).

Third choice would be Mobil 1 xW-30.

Very Specific - Mobil 1 5w30 at 7500 intervals

No warranty questions - reasonable cost.

MAT

Have you strong reasons not to use 10w30 for the summer months?

Nope - 10W30 can be used - however; I see no advantage over 5W30 in Mobil 1 (except to follow the manual "to the letter" in the summer oil temperature charts - and avoid any warranty questioons afterwards)

My dealership uses 5w30 Quaker State synthetic year round. (I bring in my own Mobil 1)

MAT

Why would there be warranty questions?

And if drained at prescribed intervals, AMSOIL is WAY cheaper than Mobil 1. Yes, AMSOIL costs more per quart, but it also has a drain interval many times longer.

I also prefer Amsoil and I am using it. I am using Series 2000 0W-30, but I have heard of others having a problem with oil usage since the oil is so thin. If you have a problem then I would go with a thicker oil like 5W-30 or 10W-30, but you should go with the thinnest synthetic, 0W-30, that it will handle.

My $0.02.

You will find many different opinions. Personally, I'm a strong supporter for Amsoil. I use 5W-30 in both my Volvo & my Toyota 4Runner. I use the Amsoil Oil & Reusable Foam/Oil Airfilter as well.

A few others may chime in regarding Amsoil and its advantages. So a search and review what others have said. Also, review the Amsoil Web Site.

The longest that I have run on a single oil change is 19,000 miles over 1 year in my 96 4Runner. I changed the oil filter at 6mths. In the end, I had the oil analyzed and it was still within usable limits for continued usage.

This is only my 2 cents.

Andrew T. Watson