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- Dec 23, 2025
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- 9
Hello all!
I've been reading the past few weeks about possible oil choices for my 1999 Mercedes Mobil 120 V12 engine. It has 155k miles and the past 10-15 years has used only Motul Xcess 5W40 (and whatever was called before), at ~5k miles; the oil changes were always done on time by the previous owner at mainly a BMW shop, thus why I think they've used the Motul oil (it has the BMW LL-01 approval).
Recently, I changed to Pennzoil Euro 5W40 (229.5 approval) for my first oil change, and I feel the oil is a bit too thin for this engine - oil pressure drops to 1.5 even when it's 50F outside and just going around town, which it didn't with the Motul (though the last change might have gotten some LM additive, I'd have to recheck my records). This V12 gets very hot so I assume this oil has a lower viscosity at 100C, and probably over time will be more of a 5W30.
Therefore, I've been reading a lot around which oil to get and wanted to ask for experts' opinions as I am only learning about it now and I am merely an enthusiast.
A few things to consider:
- engine has 155k miles, but does not consume/burn oil at all
- my long-term goal is to keep the engine in good condition to reach 250k miles (and maybe 300k if I am lucky). Given that I only drive so little every year, it might take me a while to get there
- it's seen all its life synthetic 5W40, so I would like to keep going with synthetic. Some W140/Mobil 120 folks recommended to potentially switch to blend.
- I don't track the car nor do I push it often; it's fun to drive more spirited but it's a big heavy luxury car, so not so nimble around the corners. I just love cruising in it and occasionally flooring it (though rarely goes over 5-6k rpm and only after 20-30 min of driving)
- unlikely to drive more than 5k a year - regardless, I plan to change at max 5k or 1 year, more likely the latter.
- I live in California, the coldest I ever started the car was ~45F outside. Summers are often 100+.
- I try to take it out for a 1h drive once or twice a week. Sometimes it's less, maybe a 40 min trip with a stop halfway.
Unfortunately, I made the mistake of not taking an oil sample from my recent oil change. That will be my first action item when I do an oil change before the summer. Now, it's hard to choose an oil without having a baseline, but my criteria are:
- a bit more zinc than the usual stuff for wear protection
- higher viscosity - maybe a 10W40 or even 15W40 (though this I understand is not as high quality as a 0W40 or 5W40). A fellow Mobil 120 user had switched to Mobil 1 15W40 from Mobil 1 0W40 and the oil analysis looked pretty good and he was happy with the switch. However, his engine is 82k miles, so half.
- good HTHS given that this engine runs hot
I've narrowed to a few possible oils based on the criteria (which might be not the right one, happy to learn and be corrected here) above:
- Mobil 1 Full Synthetic 0W40 - this has a higher viscosity than the 5W40 version; KV@100 = 13.8 vs 13.2
- Amsoil Euro 5W40 (EFM) - KV@100 = 14.6, HTHS = 4.0
- Ravenol VST 5W40 - KV@100 = 13.8, no idea on HTHS
- Liqui Moly Leichtlauf 5W40 - KV@100 = 14.8 according to the latest datasheet.
- Redline 5w40 - KV@100 = 15.6, HTHS = 4.4 - this seems to be the thickest 5W40 oil that I found so far.
- Castrol EDGE High Mileage 10W40 - KV@100 = 15.8, so probably sufficiently thick for my application. No idea on the moly, Zn, Ca, etc.
- Mobil 1 High Mileage 10W40 - KV@100 = 13.6, so a bit on the low side for viscosity. No idea on moly, Zn, Ca, etc.
Few other options:
- Go back to Motul XCess 5W40
- The new MB 10W40 formulated for older cars, such as the W140 - unfortunately, only available in Europe for now.
- Driven / HPL - I wouldn't mind paying the extra cost, but not sure if it would benefit from this boutique oil given my shorter OCI.
- Some good 5W50 / 15W50, but not sure which ones.
Until I get a baseline, what should I do for my next oil change for the summer? Any thoughts, opinions, or suggestions are welcomed.
Thanks for reading and happy holidays!
I've been reading the past few weeks about possible oil choices for my 1999 Mercedes Mobil 120 V12 engine. It has 155k miles and the past 10-15 years has used only Motul Xcess 5W40 (and whatever was called before), at ~5k miles; the oil changes were always done on time by the previous owner at mainly a BMW shop, thus why I think they've used the Motul oil (it has the BMW LL-01 approval).
Recently, I changed to Pennzoil Euro 5W40 (229.5 approval) for my first oil change, and I feel the oil is a bit too thin for this engine - oil pressure drops to 1.5 even when it's 50F outside and just going around town, which it didn't with the Motul (though the last change might have gotten some LM additive, I'd have to recheck my records). This V12 gets very hot so I assume this oil has a lower viscosity at 100C, and probably over time will be more of a 5W30.
Therefore, I've been reading a lot around which oil to get and wanted to ask for experts' opinions as I am only learning about it now and I am merely an enthusiast.
A few things to consider:
- engine has 155k miles, but does not consume/burn oil at all
- my long-term goal is to keep the engine in good condition to reach 250k miles (and maybe 300k if I am lucky). Given that I only drive so little every year, it might take me a while to get there
- it's seen all its life synthetic 5W40, so I would like to keep going with synthetic. Some W140/Mobil 120 folks recommended to potentially switch to blend.
- I don't track the car nor do I push it often; it's fun to drive more spirited but it's a big heavy luxury car, so not so nimble around the corners. I just love cruising in it and occasionally flooring it (though rarely goes over 5-6k rpm and only after 20-30 min of driving)
- unlikely to drive more than 5k a year - regardless, I plan to change at max 5k or 1 year, more likely the latter.
- I live in California, the coldest I ever started the car was ~45F outside. Summers are often 100+.
- I try to take it out for a 1h drive once or twice a week. Sometimes it's less, maybe a 40 min trip with a stop halfway.
Unfortunately, I made the mistake of not taking an oil sample from my recent oil change. That will be my first action item when I do an oil change before the summer. Now, it's hard to choose an oil without having a baseline, but my criteria are:
- a bit more zinc than the usual stuff for wear protection
- higher viscosity - maybe a 10W40 or even 15W40 (though this I understand is not as high quality as a 0W40 or 5W40). A fellow Mobil 120 user had switched to Mobil 1 15W40 from Mobil 1 0W40 and the oil analysis looked pretty good and he was happy with the switch. However, his engine is 82k miles, so half.
- good HTHS given that this engine runs hot
I've narrowed to a few possible oils based on the criteria (which might be not the right one, happy to learn and be corrected here) above:
- Mobil 1 Full Synthetic 0W40 - this has a higher viscosity than the 5W40 version; KV@100 = 13.8 vs 13.2
- Amsoil Euro 5W40 (EFM) - KV@100 = 14.6, HTHS = 4.0
- Ravenol VST 5W40 - KV@100 = 13.8, no idea on HTHS
- Liqui Moly Leichtlauf 5W40 - KV@100 = 14.8 according to the latest datasheet.
- Redline 5w40 - KV@100 = 15.6, HTHS = 4.4 - this seems to be the thickest 5W40 oil that I found so far.
- Castrol EDGE High Mileage 10W40 - KV@100 = 15.8, so probably sufficiently thick for my application. No idea on the moly, Zn, Ca, etc.
- Mobil 1 High Mileage 10W40 - KV@100 = 13.6, so a bit on the low side for viscosity. No idea on moly, Zn, Ca, etc.
Few other options:
- Go back to Motul XCess 5W40
- The new MB 10W40 formulated for older cars, such as the W140 - unfortunately, only available in Europe for now.
- Driven / HPL - I wouldn't mind paying the extra cost, but not sure if it would benefit from this boutique oil given my shorter OCI.
- Some good 5W50 / 15W50, but not sure which ones.
Until I get a baseline, what should I do for my next oil change for the summer? Any thoughts, opinions, or suggestions are welcomed.
Thanks for reading and happy holidays!
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