Oil just reached 7500 miles in 3 months, should I change?

[626LX2.0LATX1998]

Car has 98k miles, oil is 4 qrts of Mobil 1 5w30 Supersyn, installed Dec 22, 2005, now has 7500 miles in 3 canadian winter months with average temp 30F.

Note that 3000 miles is from straight long driving, 4500 miles is from daily drive.

I topped it off, 1/2quart mid Feb. I drive 80% highway 20% city, I don't idle.

My target is to leave it till June or 6 months, probably reach 15,000-20,000 miles by then.

Am I nuts?

 

[racer12306]

you might be a little on the crazy side. you will get a lot of answers that say do a uoa, which would probably be the only way to know whether to dump it or not. i think 7500 miles is a safe time to change it.

 

[626LX2.0LATX1998]

is 10,000 miles more reasonable?

 

[Nickdfresh]

I think you've gotten your money out of the oil by this point...

I think you begin to lose fuel economy as (even the synthetic) oil thickens with time and contaminants and flows less efficiently...

 

[racer12306]

10000 might be ok, with that much highway. i would think that the oil could go that long, but i am far from an expert on that.

 

[626LX2.0LATX1998]

quote:

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I think you begin to lose fuel economy as (even the synthetic) oil thickens with time and contaminants and flows less efficiently...

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Does oil thicken or thin out with long mileage?

I always thought oil thins out due to shearing of molecules...hmm..

 

[KJA426]

I'd change it now.

 

[Nickdfresh]

quote:

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Originally posted by 626LX2.0LATX1998:

quote:

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I think you begin to lose fuel economy as (even the synthetic) oil thickens with time and contaminants and flows less efficiently...

---

Does oil thicken or thin out with long mileage?

I always thought oil thins out due to shearing of molecules...hmm..

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Actually, I've heard both. I've heard that heat distills the oil over time and essentially burns off the smaller molecules, thereby thickening the oil...

I think the old Mobil1 site claimed that they did a comparison using two Ford Tempos, one with M1, the other with mineral oil with both grades being 5W-30. Mobil claimed that the mineral oil was the equivalent of 15W-40 after about 5000 or 15,000 miles ( I can't remember which) while the Mobil1 5W-30 stayed roughly in grade. I've heard this other places as well. But I've also read that oil does thin or shear-

out with age, so I don't know what to believe...

 

[m2200b]

Why not test it this year. You had the same run and oil last year and same question but haven't posted a test yet.

It's like asking a guy in California how your car in Toronto is doing. Who knows?

 

[Footpounds]

Change it. It'll be fun!

 

[bob_ninja]

626LX2.0LATX1998,
Considering your driving pattern you should be able to use it for 10K and more. You can search the UOAs. Here are some for Esso XD3 which is also PAO:

XD3
XD3
XD3
Comparison

Many people here seem to be comfortable with a 10K OCI using a quality synth like M1. I don't drive as much and hit the 6 month limit before 10K.

 

[ekpolk]

Why speculate? Sure, it's fun, afterall, why are you here anyway? Go ahead and do yourself a UOA, not necessarily for any economic reason (though if it reveals a hidden dangerous problem, it just paid for itself). For less than the cost of a couple cases of beer, you can both have some fun AND get a real good idea of how this oil does, in your use and climate, with you at the controls. There are plenty of good arugments for just dumping at some arbitrary short point (5k, 7.5k, whatever), but IMO, there's just no substitute for knowing.

As to thickening and thinning, there are processing going on in your oil that can lead to either result, depending upon which forces are dominant in your circumstances. Oil may thin as a result of shearing/depletion of the viscosity index improvers, or it can thicken as a result of oxidation of oil/additives. Some oils, M1 0w-40 for example are known to thin out some, and then re-thicken during their life cycle.

 

[thooks]

Do a UOA, then see what they say. I'm sure they will reccomend stretching it another 1500 or so miles, depending on what it says.

Just because it's a synthetic oil and it's highway driving doesn't mean everything is golden.

 

[Nickdfresh]

Thanks for the info ekpolk...

 

[InvalidUserID]

I'm on a similar driving situation (mostly highway, almost no idle) and have decided to do a UOA after 7k in 4 months.

 

[oilyriser]

Preventing varnish might be a good idea in this car.

 

[GoldenRod]

Why not change every 3 months?

Are you handycapped?

Don't know how to change oil?

To cheap to buy oil?

What do you hope to accomplish with a 100,000 mile OCI?

 

[Sid]

Let it hit 10,000 miles and send it in to the oil labs. If they say it's good then use it for 10K miles again. If you're putting this many miles on your oil in such a short time, you're going to want to get your money's worth.

 

[21Rouge]

quote:

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What do you hope to accomplish with a 100,000 mile OCI?

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[GarrettSocling]

Please delete this double-post