My mechanic uses a full synthetic premium motor oil, 5W-30, to change the oil for my 2008 Volvo S40, 2.4l. But often times, their intervals for saying when it needs to be changed is always different.

How often do you recommend changing it with this full synthetic oil but also, if it was a regular conventional oil? Thanks.

 

7500 miles or 12 months is the service interval.

 

Ok thanks! So 7500 miles or 12 months for synthetic oil you are saying? Is that what pretty much everyone agrees with? My mechanic has various ranges so it's so hard to know...

What about if it ever was regular conventional oil with a different mechanic in the future just so I know? Thanks!

 

The numbers are all over the place depending upon who you talk to and the oil manufacturer. The above-suggested interval will keep the oil from degrading too much.

 

The standard interval from Volvo is 7500 miles or 1 year. That is with conventional oil. Synthetic does not necessarily mean you can go longer. Clean oil is cheap insurance.

 

Ok thanks! I was always told that synthetic oil means you can go longer?

I've been doing the car every 5000 miles so maybe I can go up to 6000 miles regularly and still be ok? I just want to be careful. I checked the service manual but it doesn't say anything about how often to change the oil.

 

You're already changing it before the interval. 6000 will be fine.

 

Just curious, why do others on this forum and other places say with synthetic oil you can go longer between oil changes than you can with traditional oil? But you mentioned they are the same timelines?

 

7500 miles is a lot for conventional oil, IMHO. I'd never let dinosaur oil go that long. Synthetic oil breaks down slower than dino oil, so lasts longer. The 1 year suggestion for both is fine, since that tends to be more about condensation than wear and tear.

 

I'm telling you what Volvo recommends. There are oils that claim they can go much longer. I assume you're out of warranty, so you can do whatever you'd like. But if someone else is reading this, I recommend sticking with the factory recommended interval. Even outside of warranty, just in case.

Goodwill consideration is the reason why. Let's say you have 70k miles and for some reason, the engine needs replacement. If you want to complain to Volvo that the engine should last more than 70k miles and ask for goodwill assistance, the first thing they will want (besides a dealer diagnosis) is oil change history.

If the interval is 7500 miles and you can show you've been doing 5000 miles, great for your case. If you've been doing 10k miles, not great, no matter the oil.

You likely won't run into this, so you can do whatever you want. I change my oil with synthetic every 4 to 5k. I have 200k on my car and it has no sign of any leaks and no problems with the PCV clogging.

 

the difference of service intervals is more historical over time than by oil type for a specific vehicle. Newer cars are designed to tighter tolerances and typically run 5-30 vs the older cars which ran 10-40. Then each model's recommendation is based on driving conditions - ie standard intervals were 5000 miles but Volvo recommended changes at 3750 for "severe conditions" (short drives etc) - but there you are talking about a 20 year old car. I'd consider a 2008 "modern" in comparison where most cars have a 7500 interval with options for oil type based on severe conditions (ie Volvo will recommend different weight for cold climates and suggest synthetic for severe driving) but there's no different advise on the interval.

 

Awesome makes sense, thank you! Just curious, if you suggested 7500 miles...then why do you personally do every 4k or 5k?

 

Every year or 7500 is the minimum.

I do mine early because I work at a dealer and it costs me hardly anything. So its extra cheap insurance for me.

 

The other use case is when a car is seasonal - ie driven only in the summer etc. When my kids were in college and drove mostly in the summer, I would do a spring and fall oil change and buy OEM filters in bulk - For my S40 that comes to $30 per change for the filter plus a jug of 5-30 synthetic (ie at Walmart) for a DIY change. I do have my friendly Indy who recycles the used oil for me so add a $2 "environmental fee" so you can see its not a lot of extra cost to change more frequent than the recommended. Plus I like being able to do my own visual checks from time to time... Most people who are doing 5000 mile changes are DIY types who are happy to put the car on the ramps.

 

Depending upon what part of the country you are in, you are going to get different advice. In a southern climate, where the livin' is easy and the taxes are low, the recommended intervals are longer coming from the people at the dealership as well as independents.

While Volvo is recommending a 7500 mile drain interval or one year, some will remember that Ford and GM were recommending that drain interval 40 years ago on regular oil. So, with synthetic, one would expect a longer drain interval.

There is nothing wrong with doing a 7500 mile oil change. If you check with some, they will find that somewhat early and say that you can go 10k miles. Most of the cars hold 6+ quarts of oil.

Just for reference, my Mercedes E550 holds 9 quarts of oil. The recommended oil is Mobil 1 0W40. The service reminder is every 10k miles. Newer ones are at 12k miles. With that much oil, you can go the distance.

So, if 9 quarts will take you 10k miles, I suppose 6 quarts at 7500 miles is reasonable.

 

Comparing other brands with other engines is totally irrelevant. Your Mercedes and how much oil it takes has no bearing on Volvo's recommendations, which are clearly stated in the owner's manual. No matter the region.

If the dealership is recommending 10k just because "the livin's easy", they are wrong. But we've already found whoever you talk to at the dealership has a history of being wrong so..