Mobil 1 Extended Performance excessive oil consumption

I’ve come to the conclusion that Mobil 1 Extended Performance oil, or possible the newer formula (last 10 years or such) has been changed so that it breaks down fairly quickly and the result is high oil consumption. I assume it becomes thinner as it gets old.

I changed someone’s oil with STP 5W20 full synthetic and after about 250 to 300 hours the dipstick was down to middle. Then I used mostly Mobil 1 EP 5W20 and after about 340 hours when I changed it again it was down half way below the bottom mark on the dipstick.

I read on another forum that someone with a Toyota truck changes his oil after about 8000 miles with Mobil 1 EP, since at that point he notices a reduction in fuel economy. If you’re waiting for a noticeable change in fuel economy to change your oil that can’t be good. (Edit: this was previously in the paragraph above by mistake): The oil is probably getting too thin and messing up the variable valve timing.

Their claim of 15,000 or 20,000 miles of protection for Mobil 1 Extended Performance must be based on the oil burning off fairly rapidly after the first 5000 miles and then you have to add a quart every 2000 miles or so after that. So you would have to add another 5 quarts to get to 15,000 miles and it would still be a quart low at that point due to the normal consumption during the first 5000 miles. So you are using about the same amount of oil as if you had just changed it at 7,500.

Has anyone else noticed this about Mobil 1 Extended Performance oil that was purchased in the last 5 years?

Mobil only sells their Mobile version in certain parts of Alabama, so most of us can’t buy the Mobile version.


Lots of odd facts/claims/observations adding up to nothing. More likely related to the vehicle than to the oil.

Who changes oil on a normal vehicle by running hours ?


As a long time user of Mobil 1 products in new and used vehicles, I have experienced greater oil consumption when switching a used vehicle run on conventional oil to Mobil 1 synthetic of ANY persuasion;

The oil did, however clean a lot of the build-up sludge inside the engine based on observations of how black the oil was when it was drained. By the second oil change, the consumption reduced. The oil was less dirty at that change. By the 3rd change consumption reduced yet again to normal levels and stayed that way and the drain oil looked normal. Based on those observations over several used cars, the Mobil 1 oils had a huge detergent effect which may also account for the consumption.

Additionally, a friend experienced the same with his high mile Toyota and he immediately switched back to conventional and condemned Mobil 1, and all synthetics, forever.

I also used Mobil 1 exclusively in my race cars running oil temperatures at times over 300 degrees with no ill effects to the seals or bearings. I know this since I did complete engine teardown inspections each year in the off-season.

This is not true at all. Synthetic oil doesn’t thin as it ages. If anything, it thickens slightly.

So No, it isn’t messing up the variable valve timing. Synthetics are far more temperature stable than conventional oils.

Having to add a quart every 2000 miles would not be considered excessive by any manufacturer and not by most car owners… although we’ve had a few posters here that would argue that!


The question is; who has an hour meter on their car?
Lawn mowers, boats, and stationary power plants do, but unusual on a car or light truck.
I would think oil life monitors algorithms would include running time.

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What’s the goal here? Are we trying to prolong the life of the oil or the life of the engine?


The only time I’ve ever had a low oil light come on or let the level get down to the add mark was on my Buick, using Mobil 1, and seeing how long I could go before the oil life monitor got to 10 percent or less. To be fair, I’d gone over 6k miles already, which is 1k over my usual change interval anyway. I’m used to about how much I have to add between changes, and the consumption seemed to be a little more with the Mobil. The oil life monitor was at 20% at around 9k miles. I realize the monitor doesn’t know the difference in oil you’re using, but I wanted a good 10k mile worthy oil in the engine, as I knew following the oil life monitor was going to extend my oil change interval well beyond my normal 5k (and it was on track to double it). The extended interval is why I chose Mobil 1.

Since I don’t generally follow the oil life monitor, change oil at 5k miles, and the engines in my two GM’s are pretty low tech and forgiving, I haven’t used Mobil again. No real need to on a 5k mile change interval on regular old pushrod engines without VVT, etc. But, yeah, oil consumption seemed to increase a little with my one time usage of Mobil 1. I wouldn’t advise against using it necessarily. Just not worth the extra expense in my case, I don’t think.

My 2005 Sierra has an hour meter. It’s a pretty low optioned truck with rubber floors and no power windows or door locks. May be pretty common on light trucks?

I divided the mileage by the hours after I bought it. Just curious to see if it had been used as a work truck and idled extensively. I got over 50 mph when I did the math, so apparently it wasn’t idled much…although I’m pretty sure it was a fleet truck at some point.

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I change my lawn mower oil at 25 hours with Mobil 1. 300 seems like a lot. :grin:

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I’ve been using Mobil-1 full synthetic for years with zero problems. I might loose 1/10 pint between oil changes every 5k miles (which is normal). Starting using Mobil-1 full synthetic about 2000 with my 98 Pathfinder. My 2014 Highlander requires synthetic 0W-20. At over 165k Miles - zero issues.

That quote was from MountainBike. I’ve stolen it a few times myself. And I agree 100%. Seems many people are trying to get the most out of their oil and not the most out of the engine. Seems bassackwards to me.


Well the possible issue is that the current Mobil 1 Extended Performance, along with all the other “full synthetic oils” found at big box stores aren’t really full synthetic. At best they’re some kind of blend. It has been that way for well over 2 decades. They are high quality mineral oils which do contain viscosity modifiers that do break down over time.

What I want to know is if oil consumption is lower for the first 5000 miles or so, like a quart of consumption, but then after that the consumption increases significantly.

I wonder if they’re done something to the formula to increase oil consumption. This requires the driver to add oil which then gets you to 20,000 miles on a single oil change, but actually you’ve added more than the entire oil quantity during that time so you actually have changed your oil.

The guy on another forum with the truck that loses fuel economy after 8000 miles could be easily explained by the oil thinning, or getting thicker which I doubt.

The recent Dodge trucks have engine hour meters on them.

How? That makes no sense.


You don’t think that using thinner oil will increase oil consumption? I just watched a video about someone using 20W50 in a car with a worn out engine and the oil consumption dropped a lot.

Your post says ‘loses fuel economy’. Is that incorrect?

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Oh never mind I see what you’re referring to. My thought was that the decrease in fuel economy was due to the variable valve timing getting messed up by the oil getting thinner as it ages.

I have experienced no difference in oil consumption over an oil change with Mobil 1 oils based on Class III base stock synthetics - your “aren’t really full synthetic” oils - nor with synthetics based on Class IV - actual synthetic base stock based oils.

But I generally don’t exceed 5000 miles between changes for any reason anymore.

And no, I don’t think Mobil or any other oil company would do something to the formula to INCREASE oil consumption. That would tend to upset their customers who never check their oil levels between oil changes (there are a LOT of folks like that) and damage their customers catalytic convertors (error code P0402!) by passing more hydrocarbons through the convertors.

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I just ran Castrol Edge for 5,000 miles in my turbocharged Mazda6 and sent it to Blackstone Labs for analysis. They were amazed at how clean the oil was and how well the additive package was still working. They recommended I change my OCI to 7,000 miles. My car now has close to 80,000 miles.

My OCD is stuck at 5000 miles🤪

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I change mine at 5000 so have no idea what happens after that. I did run it up to 6000 this last time but I had zero oil consumption as usual.