Let's talk about fuel dilution and short trips

[cheesepuffs]

I have a '92 Chevy pickup, 5.0 V8 with a factory oil cooler that doesn't burn or consume any oil whatsoever. I got the truck relatively recently and I'm coming up on my first oil change with it. Current fill is Valvoline WB (5w-30, as spec'd) and I'm perfectly happy with it and will use it again.

At the moment I'm at about 3,125 miles on this OCI. Now obviously the 3,000 mile OCI is outdated, even with a conventional under non-severe circumstances, but(!) I take daily short trips. At least two 2 mile trips per day and sometimes more than that. Even my longer trips are 90% city with a good amount of idling at lights. Also, I live in CT and now that it's getting cold I idle my truck in the morning, which I know is actually bad due to fuel dilution but I have to have heat in the morning. Also, this oil has seen very summer days as well.

Now, short trips and cold temps where the engine often doesn't reach full operating temp, as well as high summer temps, combined with idling in traffic has me wondering how far I should stretch my OCI. I'm on verge of changing it now but I wanted your opinions. Is 3,1XX miles still changing it prematurely, given the severe conditions it's put through on a daily basis?

 

[JHZR2]

Id do a UOA and see what you find. Anything else is speculation - and on an older design, in an older vehicle, all bets are off (even though I imagine it is not carb'ed).

Not reaching operating temp isnt necessarily an issue, depending upon how else it is used at other points and how the oil is protecting. We have had cars that saw shorter trips and could still run full non-severe OCIs. But we had data to prove it.

 

[cheesepuffs]

Originally Posted By: JHZR2
Id do a UOA and see what you find. Anything else is speculation - and on an older design, in an older vehicle, all bets are off (even though I imagine it is not carb'ed).


I won't be doing a UOA because quite frankly it's more money than it's worth for this old truck, haha. And the truck is fuel injected, yes.

I'm just looking for some general rule of thumb opinions. I trust this place.

 

[gregk24]

For short trips like that a conventional at 3000-3500 is what I would do, Im sure others will disagree.

 

[SatinSilver]

Over what time period are we talking? Conventional oil I'd probably change at 6-12 months/3k miles based on the short trips/idling. Too bad you can't track the hours the engine is running. I think 400 is the rule of thumb there off the top of my head.

 

[cheesepuffs]

Originally Posted By: gregk24
For short trips like that a conventional at 3000-3500 is what I would do, Im sure others will disagree.


Yup, that's what I was thinking.

I was originally gonna go with a syn like QSUD or PP and run a much longer OCI but with fuel dilution concerns thrown into the mix I don't want any thinned-out, heavily gas-contaminated oil in the sump for over 6,000 miles or something. So a dino with short intervals seems best. I'm very open to hearing other opinions though.

 

[cheesepuffs]

Originally Posted By: satinsilver
Over what time period are we talking? Conventional oil I'd probably change at 6-12 months/3k miles based on the short trips/idling. Too bad you can't track the hours the engine is running. I think 400 is the rule of thumb there off the top of my head.


Current oil was filled 10 months ago.

 

[901Memphis]

5k miles oci

 

[Plumber]

I have a 1991 Chevy Cheyanne 4.3 that is fuel injected. I did not think fuel dilution was a problem?

I also run 5w-30 conventional in mine.

 

[cheesepuffs]

Originally Posted By: Plumber
I have a 1991 Chevy Cheyanne 4.3 that is fuel injected. I did not think fuel dilution was a problem?

I also run 5w-30 conventional in mine.


It has nothing to do with the specific truck, it's just that all cars that idle a lot or run at cold temps often are subject to fuel contamination in the oil. It's because engines run rich when they're cold, thus some fuel gets blown by the rings and into the oil pan. This, over time, can thin out your oil.

 

[bigt61]

If it smells heavily of fuel, then change it. If not, I'd think 5k or one year would be fine on a quality dino like VWB.

 

[SXE10]

I was going to start my own thread about this but I'll just ad it here if that ok with the OP.

What OCI would you recommend for semi-syn under similar conditions? I'm running 5W-30 Durablend thickened up with 5W-40 Penrite in the Mrs car. I'm currently changing it every 5K miles

 

[cheesepuffs]

Originally Posted By: SXE10
I was going to start my own thread about this but I'll just ad it here if that ok with the OP.


More info is better man, add away!

 

[jorton]

I think you can see fuel dilution on an oil blot. Just in case you wanted to get a feel for how much of a fd problem you have. You will see rings in the blot if fd is excessive. See the last bullet.

 

[cheesepuffs]

Originally Posted By: jorton
I think you can see fuel dilution on an oil blot. Just in case you wanted to get a feel for how much of a fd problem you have. You will see rings in the blot if fd is excessive. See the last bullet.


Thank you jorton, I've never heard of this before but I wanna try it!

 

[Zaedock]

My Jeep is a dedicated off roader and is also used on the trail and to haul wood and stuff around the yard. It endures extended idle and periodic beatings and I typically do 2-2.5 year change intervals. Fuel dilution was not an issue in UOAs.

If it were my truck, I would run a conventional 5W30 and do either a 5K interval or change once a year (I like to change in the Fall).

 

[Merkava_4]

You're not gonna get much fuel dilution unless you have a misfire. Being a 1992, I suspect it
has throttle body injection with two large fuel injectors up top. 3000 mile oil changes are fine.
If somebody wants you to go 5000 miles, have them buy you an engine first.

 

[Zaedock]

Originally Posted By: Merkava_4
If somebody wants you to go 5000 miles, have them buy you an engine first.


If he "recently" acquired the truck and already has >3000 miles on the oil, there is no reason he can't extend to 5,000 if his engine is mechanically sound.

You guys don't know what "severe" service really is.

 

[Zaedock]

FWIW, my brother has almost the same truck - a '93 GMC 5.0L with slightly more mileage. He runs yearly changes on ST conventional 5W30 and his UOA two years ago was fine.

 

[cheesepuffs]

Originally Posted By: Zaedock
Originally Posted By: Merkava_4
If somebody wants you to go 5000 miles, have them buy you an engine first.


If he "recently" acquired the truck and already has >3000 miles on the oil, there is no reason he can't extend to 5,000 if his engine is mechanically sound.

You guys don't know what "severe" service really is.


By "recently" I only meant this calender year. I've had the truck for about 7 months and have put almost exactly 3,000 miles on it. It received it's current fill of oil right before I got it. So like I said, short, daily trips. It's pretty severe.

Thanks for the opinions guys, I'm gonna stick to a 3,000 mile OCI.