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how important are oils changes for a low use car

PostPosted: Fri May 10, 2019 7:46 pm
by bob_rich
Hi All

Not been around much recently but still upright!

Not used the +2 much this past year with one thing and another and so just about to do its annual check over.
With less that 500 miles the oil looks like it did much when I put it in last year and the car has been garaged or under cover all the time. So I was wondering how long can the oil go between changes? if car use is very low. I use Millars Classic Sport 20W50. Oil pressure is fine always a good 40psi ++

guess number of folks have the issue of low mileage wonder what others do with regard to oil changes

thanks is advance for any help

Bob

Re: how important are oils changes for a low use car

PostPosted: Fri May 10, 2019 8:57 pm
by Donels
I would suggest it depends upon how it?s been used. The oil will not really really degrade with age, it can sit in the can for years and still be perfectly ok. I?ve just stripped my engine which has not been run for about 15 years and the engine is in great condition although it looks like it?s done little running.

I think the big problem would be from acid. This occurs if it?s done lots of short trips and not got hot enough to drive off the moisture. This allows the oil to become acidic and attack bearing surfaces. The other issue with short trips is dilution with petrol.

If it looks ok, smells ok, not been used for lots of short trips, then it probably is ok.

Re: how important are oils changes for a low use car

PostPosted: Sat May 11, 2019 5:46 am
by Andy8421
I inherited a 1935 Standard 12 when my father died. He had always used Castrol GTX as his oil of choice, and changed it regularly. In his later years, he wasn't able to work on his cars, and I didn't have the time to look at it when I inherited it. By the time I got around to it, it had been at least 20 years since its last oil change. In that time, the car traveled less than 100 miles.

I removed the sump plug, but no oil came out. Closer examination and removal of the sump confirmed that the oil was the consistency of thick jelly (jello).

A bit of web surfing indicated that this is not uncommon with old non-synthetic oils which form a gel over time.

While the best approach may well be different for synthetic oils, changing the oil regularly still seems good advice.

Re: how important are oils changes for a low use car

PostPosted: Sat May 11, 2019 7:04 am
by RichC
quite a few years ago i remember buying a can of 20w/50 oil ( that cream coloured can with a drawing of a mini and morris1000 on the side ?). popular in halfords and motorists discount stores at the time . It was hanging round for a few years before i used it and then when i did use it for topups one particularly cold winters day it was partially set . i.e it poured, but there were some large jelly like lumps in it .By the time i noticed it the stuff had disappeared down the oil filler and i thought no more of it , but i decided to avoid buying this brand in future . I put it down to the severe cold .... or perhaps it had been hanging around on the shelf for too long?

Re: how important are oils changes for a low use car

PostPosted: Sat May 11, 2019 7:47 pm
by RichardHawkins
There is a small book (I have just been looking for it but and can't find my copy) called 'Which Oil'. I think it is written by an Australian and makes interesting reading on the subject of low use.

Richard Hawkins

Re: how important are oils changes for a low use car

PostPosted: Sat May 11, 2019 9:00 pm
by bitsobrits
I'm probably (okay, most definitely) over the top on oil change per miles. My Elan (and all other hobby machines) gets an oil change every season before being tucked away for the winter, regardless of how few miles. Typically I do about 500-1000 year in the Elan, though a couple of years ago it was only 19 (the drive to warm up the oil before changing it!). It also has a magnetic drain plug, and a FilterMag on the inspectable oil filter (Canton Racing Spin-on). So yeah, over the top.

Re: how important are oils changes for a low use car

PostPosted: Sun May 12, 2019 1:44 am
by draenog
RichC wrote:quite a few years ago i remember buying a can of 20w/50 oil ( that cream coloured can with a drawing of a mini and morris1000 on the side ?). popular in halfords and motorists discount stores at the time .

Sounds like Comma classic oil. The mini was on the 20w50, and the Morris Minor on the 40 monograde.

https://www.commaoil.com/passenger-vehicles/products/subcategory/32

I also bought a can which I used in the MGB.

Re: how important are oils changes for a low use car

PostPosted: Sun May 12, 2019 8:45 am
by JonB
Is it the same as the Halfords stuff?

https://www.halfords.com/motoring/engin ... l-20w50-5l

I use this in mine, no problems. Did an oil change when I got the car a year and a half ago, and have driven about 2000 miles. It overwintered twice with this oil and I see no problems this year (so far). Hmm, maybe it's time to change it... says "Note: Recommended oil change every 2000 to 3000 miles."

Re: how important are oils changes for a low use car

PostPosted: Sun May 12, 2019 3:37 pm
by Davidb
Oil does degrade once it is in the engine and exposed to air and bacteria.

I had a nasty surprise when I removed the head from a car of mine that had been sitting for six months in a very warm garage. The engine was rebuilt with perhaps 3000 miles on it and very regular oil changes. When I removed the head there was an immediate strong smell of rotten eggs-my helper and I looked suspiciously at each other but the source was definitely the engine. Further examination revealed it was the oil.

I used to be a service manager for Volvo and then VW/Audi and I had never experienced this before so I googled, as one does. Eventually I found a service bulletin, intended for marine operators, that referred to this exact problem. The engine must have sat for an extended period in a warm environment and have open breathers that allow ambient air to enter the engine. Bacteria in the air then breaks down the oil and produces a black sludge and the bad sulphurous smell that I experienced. This can happen in as little as a few months.

Re: how important are oils changes for a low use car

PostPosted: Sun May 12, 2019 4:05 pm
by prezoom
When restored my Sabra, Ford 204E engine, I pulled the oil pan to see what lay beneath. This engine had sat, not running since 1974, and this was now 2010. When I drained the oil, it looked just like normal dirty oil that you would find in a current running engine. I then removed both rod and main caps to see the state of the bearings. What I found was there was still a significant amount of oil between the bearings and the journals. The bearings looked to be in near perfect shape after approximately 40k miles. So, I bolted things back together on the bottom end and then attacked the cylinder head. The valve stem bores, directly in the cast iron head, did need attention as they were quite worn on the exhaust valves. Another interesting thing was the condition of the valve springs. Using a spring checker, I found no difference in spring height and fully compressed spring pressure, between the springs that came from valves that were fully open and ones that were fully closed. I was rather amazed at the whole thing.

Re: how important are oils changes for a low use car

PostPosted: Mon May 13, 2019 8:31 am
by vincereynard
JonB wrote: Hmm, maybe it's time to change it... says "Note: Recommended oil change every 2000 to 3000 miles."



I thought your car, effectively, got an oil change every month. :)

Re: how important are oils changes for a low use car

PostPosted: Mon May 13, 2019 10:15 am
by JonB
vincereynard wrote:
JonB wrote: Hmm, maybe it's time to change it... says "Note: Recommended oil change every 2000 to 3000 miles."



I thought your car, effectively, got an oil change every month. :)


Good point! It leaks like a sieve, but I have only just finished the can of oil I bought when I got the car, so the actual volume leaked must be small, despite the horrible mess it makes.

Re: how important are oils changes for a low use car

PostPosted: Mon May 13, 2019 12:06 pm
by 69S4
A little oil goes an awfully long way - especially once the wind gets at it. It's worse if the engine is clean - get a layer on grime and seems to soak it up :lol:

Re: how important are oils changes for a low use car

PostPosted: Thu May 16, 2019 12:29 pm
by bob_rich
Hi All

Thanks for all the comments. On thinking about it cost of an oil change is not much and service costs including MOT (I still MOT the car even though it is Historic and does not have to have it carried out) are not too bad so will change oil and filter. I will keep a small sample of oil and get a mate who is a chemist to do some test on it to see if
it throws up any info

cheers and Thanks

Bob