Motul oil doesn't burn

[nathanso]

I've been using Mobil 1 in my cars for 15-20 years, mostly purchased on sale at Costco. I've always considered it one of the top synthetic engine oils and wasn't going to spend more on other oils' fancy marketing. As past cars have gotten up in miles -- my '98 V70 T5 now has 252K on its block -- I would typically need to top up the engine with 1/2 quart additions every 500-1500 miles depending on the car. On my V70, that interval was closer to 500.

Uncharacteristically, I recently had a shop do an oil change on my V70 and they used Motul 8100 Xclean 5W-30. I was a little annoyed at having to pony up $10/qt but at least I didn't have to get dirty or worry about disposing of used oil+filter.

And then, over the following weeks and months as I'd check my oil, I noticed that the level wasn't dropping.. at all. At first I thought I was measuring the oil with the car on an imperceptible incline but over time and over more checks I came to realize that the oil level simply wasn't dropping. Stunned, I started googling this phenomenon and was surprised to learn that this was indeed a property about Motul oil.. that it was far less prone to burning than many other oils.. Mobil 1 included. I called the shop to ask about this and they said it was something they were aware of.

Even though it costs 2X what Mobil 1 costs, I'm going to stick with Motul because I don't like having to always check my oil and constantly top it up. If you're running a high miles car and are needing to top up your oil on a regular basis, I'd recommend you try this Motul oil. This must come off like a shameless product plug but I have no affiliation with or commercial interest in Motul.

[erikv11]

Keep in mind the change has nothing to do with the Motul oil not burning. Rather, where the car had oil leak(s) with the oil you used before, e.g. internal leaks past the valve stem seals, the leaking is much reduced with this new oil. Similar results can perhaps be achieved by using any of a number of "high mileage" oils, or a heavier weight in your very mild bay area climate.

Good to hear you found something that works so well in your car.

[nathanso]

My car's head was rebuilt with new valve seals at 223K.

[erikv11]

That's also good!

[wizechatmgr]

My car's head was rebuilt with new valve seals at 223K.

I think Eric is trying to say is that there may be other factors. Rebuilding the top end doesn't negate the need to redo the bottom end (piston rings, etc...) to avoid other sources of oil consumption.

I've noticed in my car that as the oil progressively deteriorates, the more it tends to leak as well as burn as time goes on.

[June]

Motul 8100 5W30 is 100% synthetic oil group 4 vs Mobil1 group 3 oil. Research about types of synthetic oils like group 3, 4, and 5 oils and perhaps that is the difference. They sold you real synthetic oil, that is why you played more. June

[Sommerfeldt]

June has a good point.
Interestingly, this is something I don't think we've discussed much in the endless oil debates. Earlier, there were discussions about synth oils causing leaks, but I'd venture that most of us are using G3 oils, not G4. With the additives and processes that G3 oil goes through to make it "synthetic", that may very well have been the cause of them making old seals fail. I can't remember anyone saying that very recently, but still.

I don't think Nathanso's experience with a true synthetic oil should be dismissed as "could've been other things". If you change one single thing, and there's a measurable alteration in a directly related condition, then that's a pretty good indicator that the thing you changed was the cause of that change. Writing it off as "weeeeeeeell........ could have been something else, maybe perhaps" doesn't really hold water.

I'm coming up on an oil change as well - my T5 doesn't use much oil, but it'd still be interesting to try Motul and see if there's any kind of difference.

- S

[Rattnalle]

Synthetic oil and leaks isn't only about seals failing. It's as much about better cleaning properties and less buildup of the solid crud that's kept an already worn out engine from leaking by plugging the holes.

The two Volvo fives with 200k plus miles that I've owned both used very little oil, a litre or so every 10' miles at most. Both using synthetic. Neither was serviced excessively but rather by the book once a year or so.

[June]

Synthetic oil and leaks isn't only about seals failing. It's as much about better cleaning properties and less buildup of the solid crud that's kept an already worn out engine from leaking by plugging the holes.

The two Volvo fives with 200k plus miles that I've owned both used very little oil, a litre or so every 10' miles at most. Both using synthetic. Neither was serviced excessively but rather by the book once a year or so.

Is it safe to say over there in Sweden all synthetic oil is group 4 or 5 100% synthetic? So those two 5cyl 200k cars actually ran 100% synthetic oil?

My engine is a testimony that even with 3K oil changes group 3 "fully synthetic" crap we are sold over here creates deposits inside the engine which clearly is visible under the oil cap of my car. I find it criminal that the oil companies were allowed to change the product without posting a warning label on the bottle or at least change the label enough that the difference is noticeable.

After reading endless debates on here then noticing the crud under the oil cap back in 2016 I researched the subject and realized I could have saved a ton of money and simply let the dealer put in GTX and probably ended up with the same crud at half the price! So I finally made a informed decision 13 years late and switched my engine to Redline a group 5 oil which gave a noticeable difference immediately as the engine is noticeably quieter. Amazingly enough you are correct in that slowly the crud is dissolving under the oil cap now that my engine is actually running a real synthetic oil. June

[Sommerfeldt]

Synthetic oil and leaks isn't only about seals failing. It's as much about better cleaning properties and less buildup of the solid crud that's kept an already worn out engine from leaking by plugging the holes.

The two Volvo fives with 200k plus miles that I've owned both used very little oil, a litre or so every 10' miles at most. Both using synthetic. Neither was serviced excessively but rather by the book once a year or so.

Is it safe to say over there in Sweden all synthetic oil is group 4 or 5 100% synthetic? So those two 5cyl 200k cars actually ran 100% synthetic oil?

My engine is a testimony that even with 3K oil changes group 3 "fully synthetic" crap we are sold over here creates deposits inside the engine which clearly is visible under the oil cap of my car. I find it criminal that the oil companies were allowed to change the product without posting a warning label on the bottle or at least change the label enough that the difference is noticeable.

After reading endless debates on here then noticing the crud under the oil cap back in 2016 I researched the subject and realized I could have saved a ton of money and simply let the dealer put in GTX and probably ended up with the same crud at half the price! So I finally made a informed decision 13 years late and switched my engine to Redline a group 5 oil which gave a noticeable difference immediately as the engine is noticeably quieter. Amazingly enough you are correct in that slowly the crud is dissolving under the oil cap now that my engine is actually running a real synthetic oil. June

The cleaning properties come from additives in the G3 oil, as well as the processes it's put through. I think it's plausible that aside from the "excessive" cleaning, those may have had a detrimental effect on seals in the early days, though like I said, I've seen far less of those "I switched to synth and now my car's a ball of fire at the roadside" claims the last couple of years.

Swedish (and Norwegian) oil is basically the same as you get in the US. The fluid in a bottle of Mobil 1 5w-50 isn't different here, at least not according to the MSDS's that I've seen. I'm curious about the G5 oil though - how do you know what that is? I can see switching to a G4, like Motul, but the G5 is just a "various other stuff", mostly additives as far as I can tell (though my knowledge base on this is far more lacking than I thought ).

- S