Folks - I had received delivery of GLS 450 back in May 2022. I know typically a service is required at every 12 months of 10000 miles. I am wondering if it is a hard core rule because in 6 months I only have 3000 miles on the vehicle and I don't think I will be able to hit 10000 miles in 12 months. I am wondering if instead of 12 months - can I extend the service for additional months.

Any advise will be appreciated.

Thanks!

 

I'm not mechanically inclined enough to say with any authority that it would be bad to go beyond 12 months between oil changes since there are a number of variables (a bunch of short trips where the oil may not reach optimal temp versus few long trips, the climate, etc.). But if it were me, I would probably follow the recommended guidelines and change it once a year so that the vehicle doesn't have a questionable service history.

Hopefully someone with better knowledge of how oil ages over time can chime in and give you a more definite answer.

 

It's a rule of mine that when I get a brand new vehicle I change the oil at 1K miles and start fresh from there. The GLS was not an exception with an oil change at about 900 miles I recall.

 

If you want MB to honor warranty for parts impacted by service (primarily internal engine components) you'll need to follow their service schedule and get it done in 12 months.

As to why, moisture and time are the enemy of needed additives in the oil, and most manufacturers have used the 12 months number as the right time to change the oil. Unless you do only very very short trips, it is very likely your oil is actually fine at 12 months, but unless you do an analysis, we don't know if it will really start to break down after 18 months, or 24 months or what. Based on a bunch of different analysis that I've seen, I would be generally comfortable pushing that 18 months in all but the most severe low miles cases, but Mercedes (and other car and oil manufacturers) are going to be conservative and say 12 months -- better safe than sorry for them and their warranty.

So, my advice is definitely do it on schedule while within warranty. If the cost (or effort) is too much for you down the road/out of warranty and you want to go a few months longer, that's probably ok (although only an analysis can say for sure). I wouldn't push it to 10k miles if that is taking much longer than a year though.