I have a Mercedes SL with V8 that sees little use and then only in the summer. Typically less than 1,000 miles a year of mixed city/highway but almost always involving several hours of operation each time. I have habitually changed oil every year and always asked myself why because the old oil coming out looks spotless, just like the new oil going in. Mobil 1 15w50 is the oil with Mann OEM filters. Last time I changed with M1 15w50 EP. Has anyone studied how often a very good quality oil will last in low-use applications? It seems a shame to change on a calendar basis and throw away oil that is still perfectly good. The car has absolutely no mechanical issues that would degrade the oil, and M1 EP is billed to be a very long-life product. Heavy equipment is serviced on the basis of hours of use. Is is reasonable to base my oil changes on a mileage schedule? Cost is not the issue, I just hate to waste things.
Thanks in advance for your advice.
Oil change intervals for stored vehicles
- Thread starter MBman
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I would suggests you drain this oil after one year and do a UOA. If it comes back in great shape and it shows that the oil has plenty of life left, then you could probably extend it to every two years, but I would recommend replacing the filter and topping off after one year.
Kestas
Staff member
Another thing you could do is to drain the oil into a clean container at the end of summer, then "use it up" it in one of your secondary vehicles.
Ah a car to car transfusion, sharing fluids is that OK? even in the same family? they could catch something from each other.
I get horrible UOA's with less than 500 miles on the oil versus 2000 miles....the car will sit during the off season and not get many miles at all and sit in the shop for 4-5 months...we UOA the oil and it is garbage! Run the heck out of it for 2000 miles and the UOA's are significantly better.
Many theories on why this is....but bottom line is the UOA's tell me an oil that has 500 miles and 6 months of doing nothing is shot worse than an oil that has been ran. My latest UOA ( In the UOA section under 408 Stroker GTO) will show you what I mean....
link would help, lol
If you let me use that Mercedes for 3 months I'll change it for free...... 
I mean what can an oil change cost? $35?? Small price to pay for a new Mercedes V8...maybe you should sell it because you know the saying "if you have to ask...You can't afford it" 
I mean what can an oil change cost? $35?? Small price to pay for a new Mercedes V8...maybe you should sell it because you know the saying "if you have to ask...You can't afford it" 
JHZR2
Staff member
This is a common issue. I have a truck that I use year round, but only gets a few thousnad miles.
The bigger issue is drainback of oil and condensation forming in the oil. Its good that you get the oil good and hot regularly when you use it.
Really, anything that anybody can tell you is anecdotal evidence. Good and well-backed, but anecdotal evidence at best. If the vehicle is garage kept, Id venture to guess that your oil will be fine for 2-year intervals, if you are so inclined.
My suggestion wouldbe to sameple the oil that has been in there for a season and sitting for the next year's use, and see the water content (run the engine for a few minutes first to get everything well mixed), and send it for a UOA with professional determination of whay you can do.
IMO, youll be able to go 2 seasons, if you so desire. Why not chnage it is a good question, and using it elsewhere is a great option, but you might not desire - notmu business.
A UOA will tell you the quality of your oil after a season of use, and after nearly 3 seasons of storage afterwards. Knowing what is hapening in your oil will tell you once and for all what you need to do.
As I said, I bet youll be OK, especially if you drive it easy and long, first use, to drive off any condensation.. and remember, what condenses in your crankcase while sitting will also condense in your diff and trans, so if you have an issue in one place, youve got it everywhere.
Likely the effects of sitting on your tires, and fuel quality,stability are bigger fators to consider.
High quality additives (LC and FP) will surely help to ensure protection through the offtime.
Hope this helps,
JMH
It may depend a lot on the given vehicle. I did a UOA at 5 months / 350 miles and it was fine.
http://theoildrop.server101.com/forums/s...ge=1#Post859151
Patman
Staff member
Another thing to remember is that even if the UOAs might look bad on engines that are not run very often, that engine will probably still live longer than you! At only 1000 miles per year, even if the engine lived a short life of 50,000 miles, that's still 50 years! So it almost doesn't matter what you do in cases like that. Even if you only change the oil every 5 years that engine will still last longer than you'll probably keep the vehicle.
Thanks JMH and Patman. You are right that the only way to know is a UOA, so I will call Blackstone or another outfit.
Any problem collecting a hot sample from the contents of the oil filter; that would be easiest to get into without too much trouble. Also, there is a small drain plug on the oil cooler that I can open, but flow through it is thermostatically controlled so you need a really hot day for it to be hot.
Patman, you are right...the darn thing will outlive me. Plus it has a nine quart capacity so it takes a lot of crud to dirty up that much oil.
As to the you can't afford it crowd...I have a bunch of these old horses, so cost is a concern issue but really not the issue here. My oil shelf if full of M1 15w50, 60 - 70 quarts at any given time. Throwing away 60+ quarts of potentially good oil every year seems to be a waste. My request was to learn whether there were/are any authoritative studies on this issue of vehicle storage; you know, the kind of thing the military or museums might commission for their stored equipment. I guess not.
So, a call to the oil analyzers is next...thanks again.
JHZR2
Staff member
I wouldnt pull from the oil filter if I were you.
Solubilized metals should be the same steady state concentration anywhere in the oiling system, but who knows what other kinds of stuff you might introduce by pulling it from the filter... Good samping practices are important... done on a hot engine, from the midpoint of the sump (approximately), etc.
JMH
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