Oil change interval and premium gas in a turbo
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W214 E450
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Here's a thought exercise. You are in the market for a used Mercedes. You find not one but two perfect cars that fit your needs. Both are identical in every way. Same miles, driving conditions, color, options, year, price, etc. Both specifically call for 91 or higher octane due to their high compression engine. The only difference is vehicle 1 has had oil changes every 5K and only used 93 octane fuel. Vehicle 2 had oil changes every 10K and always used 87 octane. Which one do you buy?
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Great deflection. No, I'm not taking his word. You are focused on one thing he said that isn't that important. Most of us do not know all the motovations behind manufacturers 10K+ oil change intervals. He provided actual observations on engines failing much faster and with obvious indication of oil being a contributing factor. There are countless videos and papers all over the internet from engineers and mechanics saying the same thing. I don't see too many other than message boards pushing the 10K+ interval.
Here's a thought exercise. You are in the market for a used Mercedes. You find not one but two perfect cars that fit your needs. Both are identical in every way. Same miles, driving conditions, color, options, year, price, etc. Both specifically call for 91 or higher octane due to their high compression engine. The only difference is vehicle 1 has had oil changes every 5K and only used 93 octane fuel. Vehicle 2 had oil changes every 10K and always used 87 octane. Which one do you buy?
Here's a thought exercise. You are in the market for a used Mercedes. You find not one but two perfect cars that fit your needs. Both are identical in every way. Same miles, driving conditions, color, options, year, price, etc. Both specifically call for 91 or higher octane due to their high compression engine. The only difference is vehicle 1 has had oil changes every 5K and only used 93 octane fuel. Vehicle 2 had oil changes every 10K and always used 87 octane. Which one do you buy?
Let's be real: You will never find a youtube by a mechanic, who makes money selling service, ever advising long intervals between oil changes. At the end he even says he is not trying to upsell: Why do you think he said that?
He also mentions his customer's cars going 200K and even 300K miles. 200K miles would be for most of us 25 years! He also mentions his customer's cars burning oil: Mine does not, does yours and do you intend to keep your car 25 plus years?
Pointedly, with regard to cars burning oil, he never mentions their make, how old they are and how many miles they have on the or even how often they changed their oil. "I have heard" that many of customers changed their oil every 3K miles and they are still burning oil!
Again the old adage:
Never ask a barber if you need a haircut!
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X214
Here's a thought exercise. You are in the market for a used Mercedes. You find not one but two perfect cars that fit your needs. Both are identical in every way. Same miles, driving conditions, color, options, year, price, etc. Both specifically call for 91 or higher octane due to their high compression engine. The only difference is vehicle 1 has had oil changes every 5K and only used 93 octane fuel. Vehicle 2 had oil changes every 10K and always used 87 octane. Which one do you buy?
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"Thought experiments are hypothetical scenarios designed to explore ideas, test assumptions, and examine consequences. They often push the boundaries of what’s possible or ethical, making them ideal for mental growth and exploration."
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Um, it's a thought exercise otherwise known as a thought experiment. Here is a definition from the web that may help.
"Thought experiments are hypothetical scenarios designed to explore ideas, test assumptions, and examine consequences. They often push the boundaries of what’s possible or ethical, making them ideal for mental growth and exploration."
"Thought experiments are hypothetical scenarios designed to explore ideas, test assumptions, and examine consequences. They often push the boundaries of what’s possible or ethical, making them ideal for mental growth and exploration."
Mental masturbation refers to the act of indulging in excessive, unproductive, and often unrealistic thoughts and fantasies without taking any real-world action. It is a form of escapism and procrastination that can provide temporary pleasure but ultimately hinders personal growth and achievement.
Last edited by JTK44; Apr 7, 2025 at 01:33 PM.
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Oil change interval
This quote from your post is the problem with your question:
Once you assume the conclusion, that changing your oil as the manufacturer recommends every 10K miles is an abuse, then you will get your answer, change oil every 5K miles. This is the fallacy you have fallen into: assuming the conclusion.
Others then could correctly say that if changing every 5K miles is better than every 10K, then why not change every 2,500 miles like we did in the good old days.
In another post I wrote that there is no way to answer your question of whether changing oil every 10K will lead to an engine failure in 15 to 20 years, 150,000 miles and because there are so many variables that even if you change your oil every 2.5K miles or 5K miles you still might have an engine failure.
My dentist advises to brush teeth twice a day and at least one of those times for 2 minute and to floss once a day. I know people who double that and still have dental problems. Would those people then not have dental problems if they brushed 4 times a day and flossed twice a day? Nobody knows.
I also know people who never brush their teeth and are without dental problems.
"prefer to abuse their engine before getting rid of it saying it's no longer their problem."
Once you assume the conclusion, that changing your oil as the manufacturer recommends every 10K miles is an abuse, then you will get your answer, change oil every 5K miles. This is the fallacy you have fallen into: assuming the conclusion.
Others then could correctly say that if changing every 5K miles is better than every 10K, then why not change every 2,500 miles like we did in the good old days.
In another post I wrote that there is no way to answer your question of whether changing oil every 10K will lead to an engine failure in 15 to 20 years, 150,000 miles and because there are so many variables that even if you change your oil every 2.5K miles or 5K miles you still might have an engine failure.
My dentist advises to brush teeth twice a day and at least one of those times for 2 minute and to floss once a day. I know people who double that and still have dental problems. Would those people then not have dental problems if they brushed 4 times a day and flossed twice a day? Nobody knows.
I also know people who never brush their teeth and are without dental problems.
In my situation I change my oil and filter once a year and only put in premium gasoline and doing it this way has worked out for me just fine. I haven’t had to deal with any repairs other than simple maintenance. I put on less than 5,000 miles per year so an annual oil change is fine but if I were driving 15,000 miles per year perhaps a semi-annual oil change might be in order. As far as the fuel grade goes, premium is pretty much the only way to go simply because the octane rating of regular gasoline is so low. I remember the days when Sunoco premium was 105 octane back in the 1960’s but it had loads of lead in it which helped boost the octane rating. Today imo I don’t even use regular gas in my lawn mower because the savings of .10-.20 a gallon is easily made up by the better gas mileage in your car. But I know several people that lease S500 and S580 and put regular gas in them. That’s fine but if you have a major engine problem I can guarantee that MB will drain some fuel from your tank and if they find any regular fuel in your tank you will pay for the repair,
warrantied or not.
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I pay for my own cars, I don’t have a company to pay a lease for me etc.. so I keep my cars about 7-10 years.
In my situation I change my oil and filter once a year and only put in premium gasoline and doing it this way has worked out for me just fine. I haven’t had to deal with any repairs other than simple maintenance. I put on less than 5,000 miles per year so an annual oil change is fine but if I were driving 15,000 miles per year perhaps a semi-annual oil change might be in order. As far as the fuel grade goes, premium is pretty much the only way to go simply because the octane rating of regular gasoline is so low. I remember the days when Sunoco premium was 105 octane back in the 1960’s but it had loads of lead in it which helped boost the octane rating. Today imo I don’t even use regular gas in my lawn mower because the savings of .10-.20 a gallon is easily made up by the better gas mileage in your car. But I know several people that lease S500 and S580 and put regular gas in them. That’s fine but if you have a major engine problem I can guarantee that MB will drain some fuel from your tank and if they find any regular fuel in your tank you will pay for the repair,
warrantied or not.
In my situation I change my oil and filter once a year and only put in premium gasoline and doing it this way has worked out for me just fine. I haven’t had to deal with any repairs other than simple maintenance. I put on less than 5,000 miles per year so an annual oil change is fine but if I were driving 15,000 miles per year perhaps a semi-annual oil change might be in order. As far as the fuel grade goes, premium is pretty much the only way to go simply because the octane rating of regular gasoline is so low. I remember the days when Sunoco premium was 105 octane back in the 1960’s but it had loads of lead in it which helped boost the octane rating. Today imo I don’t even use regular gas in my lawn mower because the savings of .10-.20 a gallon is easily made up by the better gas mileage in your car. But I know several people that lease S500 and S580 and put regular gas in them. That’s fine but if you have a major engine problem I can guarantee that MB will drain some fuel from your tank and if they find any regular fuel in your tank you will pay for the repair,
warrantied or not.
- Where I live the delta between regular and premium is not $.10-$.20 a gallon but between $.95 and $1.15 per gallon
- You and others have posted that using premium you have not had any problems. I have yet to hear from anyone that using regular has caused any problem. Using premium vs. regular is like trying to prove a negative.
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Chemical Engineer, not!
Couple of contra points:
- Where I live the delta between regular and premium is not $.10-$.20 a gallon but between $.95 and $1.15 per gallon
- You and others have posted that using premium you have not had any problems. I have yet to hear from anyone that using regular has caused any problem. Using premium vs. regular is like trying to prove a negative.
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Throughout the North East the delta is the same.
We have a President who says: "I have heard", "People Say" "75 countries called me yesterday":
Is this any different than "I have heard problems from my dealer"?
You decide!
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X214
As a temporary measure, if the recommended fuel is not available…..
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X214
As far as the protocol you follow, neither of the above recommendations from the car’s own manufacturer, are being followed:
a) “temporary measure”……you use regular fuel all the time
b) “If the recommended fuel is not available”…….I assume it is available, but you choose to not use it
Then it is a matter of a ton of back-and-forth to justify what you are doing.
The 10K oil change interval (with a number of caveats from the manufacturer) you choose to follow, since that aligns to the cheaper option vis-a-vis changing more frequently (like say every 5K).
But the recommended fuel option you opt to not follow, since that does not align to an option that’s cheap (vis-a-vis putting the manufacturer’s recommended fuel into the car).
It is your car and you are at liberty to do whatever you want with it. I personally follow a more frequent Service-A protocol, and only fuel with Premium. That works for me, and seems like what you are following, works for you.
a) “temporary measure”……you use regular fuel all the time
b) “If the recommended fuel is not available”…….I assume it is available, but you choose to not use it
Then it is a matter of a ton of back-and-forth to justify what you are doing.
The 10K oil change interval (with a number of caveats from the manufacturer) you choose to follow, since that aligns to the cheaper option vis-a-vis changing more frequently (like say every 5K).
But the recommended fuel option you opt to not follow, since that does not align to an option that’s cheap (vis-a-vis putting the manufacturer’s recommended fuel into the car).
It is your car and you are at liberty to do whatever you want with it. I personally follow a more frequent Service-A protocol, and only fuel with Premium. That works for me, and seems like what you are following, works for you.
Last edited by Roweraay; Apr 10, 2025 at 01:27 PM.
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Everyone is assuming that something catastrophic is going to happen - save for the above salesmen "having heard" I have yet to see anything except "the sky is falling" and sometime in the future, maybe between 150,000/200,000 miles, you might have engine trouble.
It seems like you guys are trying awful hard justifying spending over 5 years, 10K miles per year, an extra $2,000/2,500. If you keep your car 15 years and 150,000 that is an extra $6,000/7,500 in fuel, at which time your car will not be worth $10,000!
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I like having the ability to floor it for fun or to get out of trouble with other cars. Would not feel comfortable with less octane. If I can calculate it easy, I will put in half 93 octane and half 89 octane. 91 is not available in DC area. That way I feel I am being efficient, which I otherwise do not care about, saving a little money, but not wasting the extra octane which I assume does not do anything.
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Even if does, if you do not have trouble with your engine, what difference will it make?
Everyone is assuming that something catastrophic is going to happen - save for the above salesmen "having heard" I have yet to see anything except "the sky is falling" and sometime in the future, maybe between 150,000/200,000 miles, you might have engine trouble.
It seems like you guys are trying awful hard justifying spending over 5 years, 10K miles per year, an extra $2,000/2,500. If you keep your car 15 years and 150,000 that is an extra $6,000/7,500 in fuel, at which time your car will not be worth $10,000!
Everyone is assuming that something catastrophic is going to happen - save for the above salesmen "having heard" I have yet to see anything except "the sky is falling" and sometime in the future, maybe between 150,000/200,000 miles, you might have engine trouble.
It seems like you guys are trying awful hard justifying spending over 5 years, 10K miles per year, an extra $2,000/2,500. If you keep your car 15 years and 150,000 that is an extra $6,000/7,500 in fuel, at which time your car will not be worth $10,000!
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I prefer to keep an open mind and until someone demonstrates to me, and "my dealer heard" I will not conclude that regular is inadequate fuel. If you read your manual it does not say premium is required but only premium is recommended.
Like you: "I could give a **** less what you run inyour car. You can **** in your tank if you want to"
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Your call. My thinking is that there is a reason for an electronic sensor to prevent pre-detonation and that is for those of us that do not need 365 hp and are satisfied with only 335 hp, who do not race from every stop sign, who do not intend to drive at Auto Bahn speeds, speeds in excess of 120 mph, and in the best German sense who are frugal and save money where they can and have determined that their driving needs are more than satisfied with regular gas and for them using premium gas is just a waste of money.
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Yes, get out of your own way and look in the mirror or out in your garage. This exact situation will arise when you sell your car. You admittedly under maintain the oiling system, the braking system, the fuel system, and who knows what else. So when your car is up for sale vs any of these people you think are "dumb", nobody with any brains will choose yours. Perhaps instead of thinking you are always right, which sometimes you may be, realize that you provide the example to your own question. So, again, will the bridge we sell be use to connect your ears, or eyes, or you back to earth?
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Yes, get out of your own way and look in the mirror or out in your garage. This exact situation will arise when you sell your car. You admittedly under maintain the oiling system, the braking system, the fuel system, and who knows what else. So when your car is up for sale vs any of these people you think are "dumb", nobody with any brains will choose yours. Perhaps instead of thinking you are always right, which sometimes you may be, realize that you provide the example to your own question. So, again, will the bridge we sell be use to connect your ears, or eyes, or you back to earth?
Wait there is something unique: The AUTO BAHN. When you drive at 120 mph plus, hard braking at that speed can heat up the brake fluid and cause it to boil. When cooling down moisture can accumulate.
But I do not drive anywhere at Auto Bahn speeds, so that is not a concern for me. Maybe your driving habits are different.
My car is covered under the extended warranty: every part is working fine and if not the extended warranty will cover it. The interior and exterior are pristine. When it comes time to sell and/or trade I will get top dollar, but thanks for your concern.
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X214
Your call. My thinking is that there is a reason for an electronic sensor to prevent pre-detonation and that is for those of us that do not need 365 hp and are satisfied with only 335 hp, who do not race from every stop sign, who do not intend to drive at Auto Bahn speeds, speeds in excess of 120 mph, and in the best German sense who are frugal and save money where they can and have determined that their driving needs are more than satisfied with regular gas and for them using premium gas is just a waste of money.
Plus the power degradation occurs throughout the rev band. And not some slight reduction in the power at the high-end, as you assume. It is not a 362HP engine going down to say 340HP at the top-end, but a power degradation, throughout the entire rev range.
So for a specific acceleration, an engine where timing has not been pulled, could be turning 2500rpm to generate the power needed to achieve the target speed, while another engine (like yours) that is operating with severely retarded timing, will need to rev higher to say 2750rpm to generate the exact same power. Which is why the manual states (as shown further up) that putting low-grade fuel, into an ultra-high compression Turbo engine, which is designed to run with Premium fuel, will reduce mileage.
If I know that a seller has been running with regular fuel, that car will never grace my garage. Simple as that.
