Oil change Rex

[Zwerius]

I know that according to the maintenance schedule, I should change the oil and oil filter in my Rex every 2 years.
However I seldom use the Rex. Most part of the running hours, are the automatic maintenance runs.
I've driven about 106.000 km so far, from which about 1200 km with Rex (including maintenance runs).
This comes down to about 200 km/year.
Is it realy required to change the oil every 2 years? It comes out "as new" (visually).
Does anyone have specific knowledge about aging of the oil by time?
I know it doesn't cost too much to change the oil and filter, but I'm just in doubt about the real neccesity.

 

[Anonymous]

According to a friend who is a Petroleum Engineer, it's not the oil itself that degrades with age, it's the additives in the oil.

Oil manufacturers add several compounds to their oil products so that it can best protect your engine and also last longer. These additives ensure that the synthetic motor oil maintains its viscosity or consistency. In other words, it must freely flow at all temperatures within the required test standards.

If the motor oil contains elements like copper and iron, that could contribute to its lower shelf life since these elements act as catalysts and speed up oxidation.

To stop the motor oil from freezing at low temperatures, manufacturers add pour point depressants, or PPDs. PPDs are a kind of polymer that works to inhibit the forming of wax crystals so that the motor oil flows freely. Detergents and dispersants in the motor oil delay the formation of sludge and help keep the oil clean by suspending contaminants in the oil. Defoamants protect the motor oil from frothing and forming bubbles. Most motor oils contain alkaline additives that work to neutralize the acidic contaminants. Oxidation inhibitors help maintain the stability of the motor oil while rust and corrosion inhibitors prevent condensation. Calcium additives ensure that the oil receives the oxygen it needs. They also help to delay the formation of sludge and varnish.

He said 'unopened' synthetic oil has a manufacturers shelf-life of five years. Recommended life for oil in your low-mileage/no-mileage engine - two years.

 

[Zwerius]

Thanx

 

[rtanov]

OP, you say that according to your maintenance schedule you should change it in 2-year intervals. This is interesting as my oil change interval is showing every year (2014 US REx). This year was my first out of the free maintenance perior, so I did it myself, but the oil looked so good, and we very rarely use the REX too, that I was thinking of skipping next year. I know that oil ages but am willing to take the risk as I think the REx engine should be ok since it is working so little.

 

[vreihen]

I did an oil change in my 1.8T race car about 11 years ago, and drove it HARD for a bit under 2,000 miles and 10 years on the same Mobil-1 European Car Formula without changing it or topping up. My factory-certified technician friend told me that I was insane for leaving the oil in the car for 10 years, and even more insane for running the engine at full throttle for a minute straight without giving the oil a chance to warm up.

Owning a diesel pickup that holds three gallons of lubricating oil, I send oil samples out regularly to Blackstone Labs (USA) for analysis...mostly looking for un-burned diesel fuel in the oil which is a sign of an injector that's about to fail and total the engine. I sent a sample of the race car's oil to Blackstone, along with a note describing the 10 years of abuse on that sample. Their results included a note that everything was 100% fine with that oil, and that I could run it another 2,000 miles under the same usage conditions with no worries.

I changed the oil when I took the sample, using more Mobil-1. The lab report essentially said that I won't need to do another oil change on the race car until after it qualifies for historic license plates.

I realize that the OP here is in Europe where Blackstone probably can't accept shipments from, but I'm sure there are similar labs everywhere that can process car/aircraft/marine/motorcycle oil samples and give you a similar report to answer your questions with hard data.....

 

[jadnashuanh]

I'd second the option to have your oil tested. I haven't done it as often with my current ICE, but the one before had ridiculously short oil change intervals, and I found I could easily triple that with a good synthetic oil. One sample did show some antifreeze in the oil before the reservoir level had dropped enough to notice, so that alone probably saved me a big chunk of change as I was able to stop it (verified at the next sample) before any damage was done.

The prices generally aren't all that high, depending on how extensively you want the oil tested. You may not need or want the cadillac plan that tests for lots of things.

One of the things on the REx that you should keep in mind, running the engine will put some moisture in the oil. If it's run long enough, it will boil out. The system is pretty well sealed, but there's a possibility of it getting some from the atmosphere. For that reason alone, I'd consider changing the oil annually. It's cheap insurance.

At least once a year if I wasn't going to change the oil, I'd activate the REx on a longer trip so that it and the muffler got to full operating temperature and stayed there for awhile. While oil and coolant temp tend to go up fairly rapidly, you want the whole thing, including the compartment, to get warm enough to get rid of any embedded moisture.