I don't drive the car much now, maybe 1000 mi /year. Should I still change the synthetic oil anyway? Does synthetic oil degrade if not replaced in a year?

 

It depends what those 1000 miles add up from.If you're doing lots of short, low speed tootling around town then maybe change, but if it's all fairly long trips on the highway, I would think you could leave it a couple of years. I have the same dilemma with my MG Midget, which only does about 1500 miles a year now. I change every two years. It's important to remember that the Jaguar service schedules assume fairly normal use of many thousands of miles a year, not low use cars. There really isn't any official guidance on that aspect. Of course there is the other aspect of inspection. We have a mandatory road-worthiness test every year once a car is three years old so this does pick up on things. I gather in the US you don't have these.

 

All used oil degrades with time. Current wisdom (according to the Internet), is synthetic oils are good for 2 years, good old dino is good for one. I suspect that both numbers are PDOOSA's* but cannot prove it.











*Pulled Directly Out Of Someone's A*s.

 

Short answer is yes..

 

I change ours every year with synthetic. I'm sure it's overkill. There are some interesting things to be said about new oil though. There is a break in period and new oil can cause more friction and wear than used oil, ofcourse depending on oil type, type of driving, mileage, etc. That is to say nothing of its age, though. I think changing too frequently can be detrimental, though you'd probably really never see the small effects it may have in the time that you own the car. And how frequent is too frequent? Who knows. Oil, just like anything else, isn't great one day, and the next day totally unusable.

Interestingly enough, my parents bought an '89 Chevrolet Astro new off the lot. It spun a main bearing at about 45,000 miles, which was replaced under warranty. They drive it (very hard miles, might I add...offroad and pulling trailers mixed in) well past 300,000 miles in 16 years with a total of 10-12 oil changes on the cheapest oil you could buy. They gave it away when they were done with it, and they were still driving it daily, including long distance trips, too. I'm not sold on changing oil every 3000-10000 miles, though I do change my synthetic every year with roughly 6,000 miles on it, and replace it with the best filter I can find. Hypocritical? Maybe. I figure if their car can last 300,000 on 12 cheap oil changes, I can get mine to easily last 600,000 on 24 good ones.

So how's that for a lot of talk and no answer?

 

Thanks for all the feedback. I think I will change oil every 2 years. I do about 80/20 highway/local driving once a month, mainly going to classical concerts and restaurants.

 

That would depend on the TBN of the fluid. Mileage due to viscosity improvers increasing weight and contamination content, and time because of the total base number's ability to neutralize acids. All motor oil is subject to acids created by the combustion.

 

I change based on distance driven, and sometimes that takes two years.

I figure that the engine is an almost closed system and nothing much
happens while it sits. If you would use oil that has sat in the jug for
two years, there isn't much difference if it's been sitting in the sump
instead. There is also the fact that the contaminants in this model
are spread through a much larger sump capacity than that of most
vehicles.

 

Remember when everybody changed their brake fluid every 2 years ? This was mandated by manufacturers because of water absorption and there being no means of detecting it. Now all the garages have water content measurement devices and only replace once the content gets beyond a certain value.

And oil was once replaced every 1500 miles !!

As for coolant, these OAT fluids seem to last for ever ! I queried the coolant with my local independent, and they told me it is so long lived now, that a 10 year interval is now normal. I never had a coolant replace at any of my services over my ownership of the car. Of course, I have had it part replaced when I had a water rail replaced.

 

Cheap insurance IMHO and peace of mind.

 

The definitive answer IMO is to monitor the condition of the oil,

take a sample periodically and have it analysed then follow

the lab's recommendation.

Not that I have ever done that. lol

 

So let me see----my car has 100,000 miles on it so far, I am 73 years old, and my car travels 1000 miles per year. I think I will be dead before the car engine if I NEVER change the engine oil again.

Another case of OVERTHINKING.

 

Could go for a good long while if you remember to top up
... both the car and yourself

Most of my vehicles rarely got oil changes ... but plenty
of top ups and they all lasted a good long time. The exception
is the current Jag. Don't know why ... maybe all the tensioner
and cooling scares have me spooked.

 

That is at least every two years except my wife's 335i. She only puts maybe 1500 a year on it.
I have been changing it every year. But it has been 18 months and 2000 miles since the last. There is no dipstick. But I plan on changing it at 2 years. BMW recommends 15,000 miles or annually. It is ten years old with less than 40,000.
On my XJR it is 5,000 mile interval for me with a Wix filter and Castrol 0-w40 oil made in West Germany.

 

Nice violet cast to the oil? I believe it is labelled Made in Belgium.

 

Cheap insurance is cliche and false. It takes great energy to extract, refine, produce, package, transport and recycle the oil & filter. There is so much more than the $40-70-ish you might spend to consider. Peace of mind? Well if you're losing sleep over this... #FirstWorldProblem

Simple answer is get an oil analysis done (what, $20-25?) and you'll have a definitive, scientific answer. I'd say with 80% highway driving you can easily go 2 years or longer, possibly 3-4. On an another vehicle that only drove about 2,000 miles a year I only changed the oil every 2-3 years (using synthetic).

Changing oil once a year under your conditions is total overkill. But I suppose if you're a shareholder in an oil company you might want to change twice a year LOL

 

The cost of doing adequate oil analysis samples will easily exceed the cost of just changing the oil.

 

When I was a kid, back in the late 50s, a Marine Corps friend told me that it used to drive the maintenance guys crazy that the Corps required that the oil on fleets of trucks be changed at regulated intervals - even for vehicles just sitting in motor pool parks.

Maybe the oil of the period (certainly no synthetics) or the logic of a bureaucracy? The logic was that essential components of the oil evaporated over time. Any thoughts?

 

There's no perfect answer. Short distances / little use leaves bad stuff in the oil. If you don't mind, leave it. It's your car, your engine.

You're supposed to change it but ... it's up to you. (Just don't complain if you skip it and the engine breaks down!)

Jaguar do the best they can but it will inevitably be a compromise. Out-guessing them would not be for me, but that's about my car.

 

IMHO, 2 years is the most that I would leave the oil in the engine. Unless, the car is stored for a long time.