As an old oil formulator, I'm constantly amazed by posts from the US which say 'I change my oil every 3,000 miles' or 'I don't want black oil in my engine so I change it when it starts to go dark'. It makes a complete mockery of everything that the motor lubricant industry has done over the last few decades. Better base oils, higher treats of increasingly expensive additives, eye-wateringly expensive oil development and Byzantine qualification processes based on an ever expanding suite of engine and rig tests...it all counts for nothing when you routinely dump your oil at 3,000 miles!
And you can see the evidence for this as plain as daylight in BITOG's UOA section. There's virtually no evidence of oil viscosity change either upwards (because of oxidation) or downward (because of shear) and both wear metals and additive depetion are laughably low compared to what a professional formulator would consider acceptable.
Well today, you'll be pleased to know 'I come to praise Caesar, not to bury him'. Reluctant as I am to say it, the US way of doing things does appear to work. One thing I see a lot of on BITOG are posts from people who have cars that have done 400,000+ miles and are still going strong. In fact I'm surprised you have so many old bangers (beaters) in the US because my last three cars were more or less knackered after ten years and 120k miles!
So I posed myself the question, if Americans are going to continue changing their oil ever 3k, should anything change? I came up with two answers...
If your car is new and under warranty, then just do what the OEM recommends. I don't always agree with what OEMs recommend as so much of it self-serving twaddle but if it preserves the warranty, swallow the excess cost and just do it.
However, if your car is older and out of warranty, then I would say there's case to be made for using a significantly cheaper oil that doesn't necessarily comply with GF-5 (or GF-6 if it ever surfaces). My thoughts are...
- most engine oils in the US are now made from cheap but high quality Group II base oil. These are way more resistant to oxidation than Group I's. Properly treated with additive, the chances of these oils oxidising to the point where they start precipitating sludge within 3k miles are almost nil. I doubt if many would even darken that much. Additives should focus on keeping the oil stable over 3k miles. 1% of light ZDDP (equates to about 950 ppm of Phos in oil) plus 2% 400 TBN over-based detergent (equates to about 8 TBN in oil) would probably do the trick.
- if the above is valid, then there's a good case to make that the oil doesn't need to contain any ashless dispersant. Sludge only needs dispersing when it's being formed which is the point where oxidation rockets out if control. That point would not be reached in 3k miles so it should be safe to remove it.
- if this occurs a couple of things happen. For any given viscosity grade, the NOACK volatility of the oil decreases significantly which I'd argue is always a good thing for any engine. The second thing is you knock out a least a half (and possibly more) of the expensive additive that normally goes into oil. Given that additive typically costs four times as much as base oil, the overall affect on the price of the finished oil would be significant.
- the final thing I'd say is that if the lubricant industry has proved anything over the last decade, it's that normal engines don't need overly thick, or overly thin oils. Your cams, bores, rings and bearings won't wear away to nothing in 3k miles if you run a 20 weight oil containing 1% ZDDP. Likewise, unless you live somewhere that's life-threateningly cold, you probably don't need a 0W oil. Even the case for having a 5W is marginal for great swathes of the US. Indeed, 20 years ago, most of the US ran with 10W30 oil and life went on as normal. The only reason why 0W & 5W are pushed so hard today is because OEMs can claim CAFE credits regardless of how much this adds to the cost of the oil you pay for. And it's not like the average American is actually interested in fuel economy is it?
- this being so, maybe over 3k miles, a lowly 10W20 oil containg 3% DI and no VII polymer might suffice. And that would be so, so cheap to make...
I suspect this speculation will never amount to much but in the event that Mr Stumpy Fingers ever gets his hands on the levers of powers and trashes the entire US economy, this might be one way you can all save yourself a few bob whilst driving around looking for work...
And you can see the evidence for this as plain as daylight in BITOG's UOA section. There's virtually no evidence of oil viscosity change either upwards (because of oxidation) or downward (because of shear) and both wear metals and additive depetion are laughably low compared to what a professional formulator would consider acceptable.
Well today, you'll be pleased to know 'I come to praise Caesar, not to bury him'. Reluctant as I am to say it, the US way of doing things does appear to work. One thing I see a lot of on BITOG are posts from people who have cars that have done 400,000+ miles and are still going strong. In fact I'm surprised you have so many old bangers (beaters) in the US because my last three cars were more or less knackered after ten years and 120k miles!
So I posed myself the question, if Americans are going to continue changing their oil ever 3k, should anything change? I came up with two answers...
If your car is new and under warranty, then just do what the OEM recommends. I don't always agree with what OEMs recommend as so much of it self-serving twaddle but if it preserves the warranty, swallow the excess cost and just do it.
However, if your car is older and out of warranty, then I would say there's case to be made for using a significantly cheaper oil that doesn't necessarily comply with GF-5 (or GF-6 if it ever surfaces). My thoughts are...
- most engine oils in the US are now made from cheap but high quality Group II base oil. These are way more resistant to oxidation than Group I's. Properly treated with additive, the chances of these oils oxidising to the point where they start precipitating sludge within 3k miles are almost nil. I doubt if many would even darken that much. Additives should focus on keeping the oil stable over 3k miles. 1% of light ZDDP (equates to about 950 ppm of Phos in oil) plus 2% 400 TBN over-based detergent (equates to about 8 TBN in oil) would probably do the trick.
- if the above is valid, then there's a good case to make that the oil doesn't need to contain any ashless dispersant. Sludge only needs dispersing when it's being formed which is the point where oxidation rockets out if control. That point would not be reached in 3k miles so it should be safe to remove it.
- if this occurs a couple of things happen. For any given viscosity grade, the NOACK volatility of the oil decreases significantly which I'd argue is always a good thing for any engine. The second thing is you knock out a least a half (and possibly more) of the expensive additive that normally goes into oil. Given that additive typically costs four times as much as base oil, the overall affect on the price of the finished oil would be significant.
- the final thing I'd say is that if the lubricant industry has proved anything over the last decade, it's that normal engines don't need overly thick, or overly thin oils. Your cams, bores, rings and bearings won't wear away to nothing in 3k miles if you run a 20 weight oil containing 1% ZDDP. Likewise, unless you live somewhere that's life-threateningly cold, you probably don't need a 0W oil. Even the case for having a 5W is marginal for great swathes of the US. Indeed, 20 years ago, most of the US ran with 10W30 oil and life went on as normal. The only reason why 0W & 5W are pushed so hard today is because OEMs can claim CAFE credits regardless of how much this adds to the cost of the oil you pay for. And it's not like the average American is actually interested in fuel economy is it?
- this being so, maybe over 3k miles, a lowly 10W20 oil containg 3% DI and no VII polymer might suffice. And that would be so, so cheap to make...
I suspect this speculation will never amount to much but in the event that Mr Stumpy Fingers ever gets his hands on the levers of powers and trashes the entire US economy, this might be one way you can all save yourself a few bob whilst driving around looking for work...
Last edited: