Dumb question time. What kind of an oil change interval is generally recommended for "occasional use" vehicles? It'll take me years to build up to 3000 miles, possibly even after the Tank is all fixed up (OK, fantasizing now), yet every 3 months seems extreme. Is "every 3 months" still recommended even? What, does the oil spoil or something? I guess I could go look on the motor oil containers on the back porch, but it's late and I'm tired. Think I'll go to bed, but looking forward to anyone's suggestions (even if they are "what the heck are you jabbering about?")

 

This'll be a real interesting thread. I predict you'll get about 42 replies and probably 37 different answers.

OK, I'll stick my neck out first.

- There have been studies done documenting how much copper, iron, nickel, aluminum, etc. is found in oil after running it in an engine for various periods of time.
- There have been studies done documenting water vapor, acid, etc. contamination found in oil after running it in an engine for various periods of time.
- There have been studies done documenting breakdown of oil additives after running it in an engine for various periods of time.
- There are case histories of engines failing from all three causes listed above. Some of these case histories contradict what the studies showed. Back to square one. There are just too many variables to give a hard answer - an edumacated guess is about all you can expect.

Let's assume:
- You run your engine long enough (20 minutes minimum) to thoroughly warm it up each time you use it
- You run your engine at least once every couple of weeks
- Your engine does not run hot due to performance modifications or broken parts
- Your engine is not used under severe conditions like drag racing, etc.
- You don't use your air cleaner to vacuum up all the dust after the Baha 1000
- You use a brand-name multi-viscosity oil, or a synthetic oil, and a quality oil filter

The more often you change your oil and filter, the cleaner the oil will be. There is, however, a point of diminishing return. Changing it every five years is not nearly often enough, every week is way too often. My guess is you could change it every six months and be well below the danger line where you would notice any oil-induced engine damage over the life of the engine. With your low mileage use, you probably could get by with changing oil and filter once a year. At that longer interval, I'd be just a little concerned that water vapor condensation during weather changes (temperature and humidity) might start to overload the oil with water vapor, and create some internal corrosion problems. The cost of the oil and a filter in my mind doesn't warrant going from six months to a year.

A side note - an old fellow once told me that changing oil, and not changing the filter, was like taking a shower and not changing your underwear.

 

Jeff,

On my grocery getter I change the oil every 3000 miles. Sometimes three months have elapsed (winter) and sometimes not (summer). I pretty much ignore the 3 month interval. On my rods I've always used Mobil-1 synthetic oil and I change the oil and filter once a year (whether it needs it or not! ). This may not work for everyone, but it works for me and I have never had an engine problem related to infrequent oil changes. However, I don't recall ever putting more than 5-6K miles on a rod in a year. I suppose if my annual mileage was a lot higher than that, once a year would not be often enough.

Vern

 

"This'll be a real interesting thread. I predict you'll get about 42 replies and probably 37 different answers."

I'll do my best George.

You should be able to tell by the taste when it needs changed. Get a baseline taste right after you change it and remember it. About once a month, pull the dipstick and give her a lick.

1. Just a bit of gasoline or carbon taste is completely normal, so don't be alarmed. You're still good. Don't change it yet.

2. If it burns your tongue, that means the engines been running. Try again tomorrow morning.

3. If it starts tasting like it's got a lot of metal in it, it's time for a change.

Hopefully you licked your internal engine wear parts like main and cam bearings when you built the motor so you know what your looking for. If you didn't, then you might be in trouble here. I would then suggest you just change a low use engine oil and filter a couple times a year and it will likely never even get dirty. Cost you 20 bucks a year and forget worrying about it.

 

Damn, I forgot to lick the rod bearings when I put 'er together.

 

There is one way to know if U really need a oil change.. Take a sample to a big rig shop and ask if U can have them sent it out to have it check ( about $15) Than U will know for a fact how ur oil doing.. That for a truck the not drivin all the time.. other wise Id just do 3 months or 3000 miles to keep ur baby 100% all the time.. Oil does break down with age only

 

with a good filter(not the cheap one) and good oil, possibly even synthetic, theoretically, ive heard you should change it one to two times a year if it doesnt make 3000 miles....

as for the different answer, a little trick ive been brought up by is when you check it, dont be afraid to wipe the dipstick off with your finger, and see if it smells different,(if it smells TOO gassy, then it should be changed) and check to see how good it wipes off your finger. If your finger stays dirty/dingy, then the oil is dirty and should be changed, if it wipes off clean, your good for a while yet.

it works, those are what i go by all the time...

Darrell

 

Personal opinion, you'd be better off (and so would your truck) if you changed more often (say 3 times a year) using cheaper non-synthetic oil, than using synthetic and changing once or twice. Synthetic just isn't offering you a benefit in this kind of usage. Specifically, I think using diesel motor oils would give you better protection. It is full of the good stuff, whereas all gas engine oils have slowly had their supplements reduced to prevent contamination of the catalytic converters. Rotella or other quality diesel oils are the hot ticket for flatheads, which are notorious for building up deposits in the crankcase (non-PCV, you know). My 2 cents anyway... this is what I'm doing with wimilar usage.

-- Ross

 

One issue not addressed is the type of engine that is in the truck. If you are running an original engine or one similar the tolerances and filtering systems were not as good. Still if the vehicle isn't driven a lot of miles a couple of times a year is plenty. I would probably change it in the spring before the cruising season. If the vehicle has a newer engine, I would follow the manufacturer's recommendations for that engine. With newer engines driven mostly on the highway and not in a heavy duty situation an oil change every 3000 miles is probably overkill. I've had a number of vehicles in the last 20 years and I followed the manufacturers interval and have not had engine failure and all have been driven well over 100,000 miles.

 

Wow! I change my oil on my '54 with the original 239 OHV Y-block (rebuilt in 1979) once a year when my PA inspection is due in April. Last year I had 1,000 miles on it. Some years it might be a bit more. I have noticed no problems, but that doesn't mean there aren't problems brewing inside. I still have the road breather tube for crankcase ventilation.

What do you think?

thanks, Abe

 

ONCE A YEAR!

The moisture that accumulates in the oil will vent out once the engine has been run to operating temperature.

I do mine every fall so all the internal parts are coated with fresh clean oil. In the spring once its run for a few miles any moisture that was in the oil will boil out.

Maybe not the right way, Just my way!
Kevin Bigwin

 

I do it once a year which translates to about a one or two thousand mile interval. I think that condensation in the oil is not much of a problem if you are running the engine up to operating temp regularly. However, condensation in the fuel tank is much more of a problem. While you are tasting your dipstick, you should also remember to keep your gas tank as full as practical. Also, for oil change frequency, take into consideration that some carbs will, over time, drain their bowls into the engine. This draining gas would be a very good reason to change your oil more frequently. Jag

 

thanks jag, back to what i said, if it smells gassy....i would agree, its definitely a good idea to change it....just to be safe at least...better to spend 20-30 a year on oil and filters than hundreds to redo something...

 

I appreciate all the comments on this! I had been changing every spring, but last month checked the oil and it had the appearance of watered-down, melted chocolate. Didn't think to smell it... I'm sure I changed the oil last year, but not the filter, so maybe that was the difference. Anyway I changed the oil and filter a couple of weeks ago and was thinking about going to twice a year, pretty cheap vs. major engine work.

 

Your description makes me think that maybe you are getting coolant into your oil. A friend of mine has oil that turns that color often. His is caused by a small crack in his head. Coolant bubbles up and mixes with the oil, then runs down the oil drain. His has been like this for years, but he only drives it to shows on the weekend. Good Luck, Jag