For years we have recommended a 10,000 mile oil change interval. Almost 20 years ago I had multiple conversations with engineers at Fuchs, Rowe and Liquimoly. I even had access to internal training programs at Liquimoly, and everything pointed to the same conclusion: Stick to a 10,000 mile change interval.
BACKGROUND: We like things to make sense and not just take someone’s word for it. So why was the 10,000 mile interval given? And why is it in your owners manual? The historical reason why was because oils have detergents and dispersants to clean your engine, as well as additives to prevent wear. Detergent additives keep metal components clean and free of any deposits. They also help to neutralize any acids that might form in the oil. Dispersants are particularly important in diesel oils as they are used to keep engine soot particles suspended and prevent the formation of larger soot deposits, known as agglomeration. Together they suspend contaminants and neutralize acids.
Generally the detergents work the first 1000 miles or so of an oil change, over which time you are having increased wear. Then the additives take over and they were supposed to last to 10,000+ miles. Eventually, the additives exceed their limit of functionality which requires users to change the oil.
Fast forward 20 years. We have seen shops report back that they are seeing increased oil sludge and engine failures from high oil change (10,000) intervals. The author of this piece had his Mercedes Bluetec engine seize due to oil sludge (it was running Mobil 1 at the time and had a 10,000 change interval, exactly as the manual specifies). Special thanks to Chris Sunday who has been reporting issues for years – so we delved deeper into the problem. We didn’t want to report “change this often now” without it making sense.
In 2024 I attended a training where I was able to speak with representatives from Liquimoly and Pentosin. I explained the problem, the history, as well as the fact that I realize they are in the business to sell oil, but I am in the business to do what is best for my customers. They both reported the same thing: thanks to EPA standards, zinc levels being reduced or removed from oils, and the like has resulted in over 3 times the additives being added to oils now compared to in the past in order to achieve the best protection possible. Internal testing has shown that the additive package begins to break down at 5,000 miles and is seriously compromised the longer you go. This is even more pronounced with thinner oils (VW 508 spec 0W20 for example) and oils that are subject to higher temperatures (e.g. DPF’s).
So why does your manual say 10,000 mile changes? According to sources we have within the industry, OEM’s are being pressured by the EPA to reduce environmental footprints by extending the change interval longer and longer. OEM’s are also internally being pressured by corporate bean counters to show a lower cost of ownership to consumers. By extending oil change intervals they show, on paper, that the cost of maintenance is lower.
Consequently, based on experience and science, we are now recommending a 5,000 mile oil change interval, especially on all 2007+ vehicles. Older vehicles driven with mostly highway miles may be able to go further, but remember that the additives found in the oil of 2004 is not necessarily the same as 2024. If you think you might have some oil sludge, Liqui Moly Pro-Line Engine Flush is a very good idea.
Also remember – just because your truck has a capacity of 13 quarts or 13 gallons and thus can go further before the additive package breaks down doesn’t mean your VW with a 4.5 liter capacity can go that far. These recommendations are for Euro passenger vehicles, VW/Audi, BMW and Mercedes.
