Does synthetic oil go bad over time?
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Member
Joined: Nov 2012
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C300, ML350
Does synthetic oil go bad over time?
I heard for conventional oil the recommendation for changing oil is every 5k miles or yearly (which ever comes first)
But what about for synthetic fuel, do they go bad over time? Its recommended we change our oil every 10k miles but is there a time interval to change oil or do we just change it whenever we reach 10k?
But what about for synthetic fuel, do they go bad over time? Its recommended we change our oil every 10k miles but is there a time interval to change oil or do we just change it whenever we reach 10k?
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Joined: Jun 2008
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Oil does not go bad in normal terms. It becomes contaminated. One of the biggest reasons for an annual oil change if you have not done the mileage is that water is a by-product of the combustion process. Cars that do low mileage & seldom run fully warmed up for adequate periods can get water content in the sump up to 7 or 8%. Water is a poor lubricant.
Super Member
Joined: Mar 2011
Posts: 803
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From: Bay Area, CA
2011 C300 Sport, P1, MM, Wood, Heated FS, DIY rearview camera.
10K miles or one year whichever comes first.
My 2011 is low mileage, first year oil change was at like 2200 miles, second year was at ~ 4000 miles. Now the third year is coming in 3 weeks, now I got 12000 miles.
It's almost strictly a weekend car.
My 2011 is low mileage, first year oil change was at like 2200 miles, second year was at ~ 4000 miles. Now the third year is coming in 3 weeks, now I got 12000 miles.
It's almost strictly a weekend car.
Member
Joined: Nov 2010
Posts: 197
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From: Australia
C220 CDI SLK 200
Just go by what the service indicator shows. I had my car laid up for 9months just after a service and when I returned home the indicator said service due 1 Month. I went for a long drives over the next weeks and it changed back to due 15000km after service
Super Moderator
Joined: Jun 2008
Posts: 19,942
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Most Benz cars today have their FSS turned off & are on fixed mileage & time.
Australia might be different.
Australia might be different.
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Junior Member
Joined: Nov 2013
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2014 E350 Cabriolet 2002 CLK Cabriolet
I know MB recommends changing oil at 10K but that seems excessive. Since an oil change is relatively cheap I will change mine at 5K or annually. I must admit I don't hit 5K a year on the Benz but on the Lexus it's every 5. Maybe it's just piece of mind and to account for the temperature extremes we get thought the year up here.
Senior Member
Joined: Jan 2014
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G63
I stick with 10k or 1yr which ever comes first.
My 911 is supposed to be 15k or 1 yr and I changed is every year with <5k miles on it. As Glyn points out, the contaminates are corrosive and I prefer to change it annually.
My 911 is supposed to be 15k or 1 yr and I changed is every year with <5k miles on it. As Glyn points out, the contaminates are corrosive and I prefer to change it annually.
Super Member
Joined: Jan 2008
Posts: 702
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From: Illinois
'08 C300 4Matic Sport, '02 530i
With a large sump and high quality MB 229.5 approved oil, 10K miles is not excessive. But the 1-year limit still applies, for the reasons Glyn mentioned.
In the end, you'll do what helps you sleep better at night. You can't put a price on that.
In the end, you'll do what helps you sleep better at night. You can't put a price on that.
