Eek! Major fuel dilution. Problem?

[MisterBen]

I have a 2010 Mazda 3 with the 2.0L naturally aspirated 4 cylinder. The car has about 14k miles on it.

The last oil change was done at Firestone with full synthetic Kendall motor oil and what looks like an Ecore filter (though they swore they used Purolator--nice!).

Anyway, that change lasted 6 months and right about 5k miles. I changed the oil last night, and it was putrid with fuel. The wife came out to the garage after I had it drained, and noticed the garage smelled of fuel. I couldn't stay under the car while it was draining. Yuck! It also came out looking pretty black. I refilled it with almost clear Motorcraft synth blend.

It's mostly the wife's car, though I drive it a lot when we both go somewhere. However, the car sees a lot of short trips (especially when it's just her). So I'm guessing that's where the fuel dilution is coming from.

So, I'm guessing I should change the oil on 3-4 month intervals, then? I guess subscribe to severe service? Are there any other measures I should take with the car, is this an indication of an early issue with it?

The car is spec'd for 5w-20. My truck uses 5w-30, so I get the Chevron dino oil from Costco when there's a coupon (buy 3 cases when needed). Would it be OK to use this in the car? It's about as cheap as it gets around here, and if I have to change it every 3-4 months, I don't want to spend an arm and a leg. I'm a little concerned about going out of spec, but the turbo 4cyl Mazdas require 5w-30.

Thoughts?

 

[addyguy]

If the car is short-tripped at all, there will most likely be fuel in the oil. The only way to tell if this situation is a problem is to do a UOA on a fill of oil, and see how much fuel is in the oil, and if it is causing extra wear.

The truth is, this situation is probably not nearly as bad as you think it is - stick with the 5W-20, go 5k, and do a UOA on your next fuill if you really want to know whats going on.

 

[Bladecutter]

Exactly how short of a trip is she driving?

Is she starting the car up, driving 2 blocks away, and then shutting down?

If she is, you are probably better off changing the oil more frequently than 5k miles. And stick with the 5W-20 for this non-turbo engine.

If they are really short trips, then every 3 months might be the better plan for this engine. Get that gas out the only way it truly can get out.

BC.

 

[MisterBen]

Probably more than a couple of blocks, but not much more. She's not working right now, so many trips are just to the grocery store and back. That's probably a mile or two one way, it's not very far.

When I drive, the car gets up to temp generally as we are usually going farther (though I do sometimes short-trip to the store and back as well), but it obviously isn't getting burned off as well.

UOA is probably best, but I imagine I'm just going to have to change it more often. Too bad it's more of a pain than the truck to change!

 

[bigdawg74]

Go with 5-20, stock up on oil when you see a good deal, and change it every 3 or 4 months. Oh, and steer clear of Firestone, IMHO.

 

[MisterBen]

Yeah, I don't plan on using Firestone again. I'll just have to keep an eye out for 5w-20 sales. I just haven't been paying enough attention probably, as the Costco deals are about the best at $20/case.

 

[chubbs1]

I would get a UOA just to see how things are going. The only problem is the car has low mileage anyway so it may be still breaking in, showing a little higher wear anyway. I personally see nothing wrong with using a 5w30. WHATEVER HELPS YOU SLEEP BETTER!

Bladecutter is right in saying the only true way to get any fuel out is to change the oil of course do a 4k OCI and get a UOA after driving a common route for the vehicle to warm it up. This should give you a better sense of the fuel. In other words don't go on a 1 hour drive before changing the oil.

Good Luck...All oil gets pretty gassy smelling in my vehicles and I don't have dilution. You are prolly fine.

 

[The motor guy]

If that's all your doing is driving it for a mile. It takes atleast a mile to warm up. You need to take this thing down the freeway once every few days you are doing these short trips. You need to run it at 70mph for 45 minutes or so. That will evaporate the fuel/moisture in the engine. Also is the engine making oil? Keep an eye on the oil level it will rise when you are getting fuel in the oil.

 

[fdcg27]

It may be that you are simply seeing (smelling) the results of short trip driving.
It may also be that you have injector problems.
Either way, it might be worth the +/- $20.00 to have a UOA done, to see whether fuel in the oil is at a level that would indicate a bad injector.
I can tell you that in terms of smell, a little fuel in the oil goes a long way.
If you don't have a really serious issue, more frequent changes might be indicated anyway.

 

[MisterBen]

I haven't paid attention to whether or not oil level is increasing, but will now.

On the next oil change, I'll get a UOA.

It does get out for longer drives a few times a month--should be plenty to get the car warm enough. I guess not though, I'll just have to make a point to get it really out and going.

 

[TFB1]

IF the fuel dilution is going to be a continual issue, I'd step up to a 5W-30 oil... Assuming the problem is as severe as stated, the drained oil may have not even been 0w-5 weight...