Engine Oil Analysis - My Oil Doctor

[AndyF]

Hello all

As part of the Friday Spotlight (7th August 2020) JEC weekly newsletter, I saw an advert for MyOilDoctor for laboratory analysis of vehicle fluids. Having seen this general technique used at work on our durability vehicles, I wondered what it would show about my own 25 year old V12 XJS.

I sent off for the kit (£29.40 inc JEC discount) and had a box delivered containing all the required kit - sample bottle, syringe, tube, laboratory ticket - even protective gloves. I took a sample of the engine oil saved from the recent oil change at David Marks and sent it off in the pre-paid envelope for analysis.

[AndyF]

Cont,

After 7 days, I got the report back.

Which seems to tell me that everything was ok in the oil at the time it was changed. The car had only done 1,114 miles since its last service (poor, I know - blame lock down!), so I wasn't expecting the additives to be depleted, nor for there to be excessive particulate levels in the oil. However, it was reassuring to see the low levels of all contaminants - suggesting that most things are healthy.

I suppose this is only a snap shot in time - to get a full picture you would do it at regular intervals, if you wanted more information. Perhaps at each or every other oil change, which if done over a number of years, would allow you to see if there were any deterioration with time / miles.

Would I use the service again? Well, it has satisfied my curiosity for now and has confirmed that the V12 has some life left in it yet! The service from The Oil Doctor was good and prompt. I might be inclined to use it when I next purchase a car - it seems like it would be a very good way to get a "baseline" for the condition of the engine and a guide as to how well it has been serviced (or at least approximately when the oil was last changed).

Has anyone else used such a service? Did it tell you anything different? I asked around my friends (who seem to all run Porsche 996s and Elises of various vintages), as I thought it might be of interest to them, especially with the head gasket risks on the K Series engine in the Elise and the IMS seal and bearing on the 996. The only one which has been tested was one of the 996s, which had the service done by Millers Oils...the result? All very wallet friendly and boringly normal. Some of my other friends think that the whole oil sampling thing is just burning money... but each to their own. The engineering geek in me just liked exploring an area of engine behaviour that I had not experienced before.

[J44EAG]

A frequent and trusted procedure in the aircraft industry which helps monitor wear in an engine. High levels of any particular metal particulate help decide what parts within an engine may be wearing ie cast iron indicates piston ring wear, white metal indicates crank and conrod bearing wear and bronze might indicate conrod small end bush wear.

As a former aircraft engineer, I can say we always found these spectral analysis tests most useful when it came to assessing the amount of useful life an engine had left in it. It was known as a SOAP test.

I don`t regard such a test as a waste of money. If nothing else, you test result should give you a measure of reassurance than be a cause for concern. had the test revealed high levels of any particulate, then you might have wanted to consider an engine rebuild. As it stands, you should be a happy bunny!

Mike K

[PaulGover]

I'd guess it would be best to do the analysis nearer the scheduled oil change interval, or perhaps 50% thereof, to let wear particles and the like accumulate; otherwise, it's more a test of how successful your last oil change was!

[J44EAG]

We would use a SOAP test on engines which had high air time or were perhaps showing the first signs of reduced power or reluctant starting. We would also combine that investigation with a differential compression test of each engine cylinder. Compressed air would be used to detect engine compression loss which was usually down to leaking piston rings, inlet or exhaust valves. We would force the compressed air into the engine cylinder through a fitting which could screw into a spark plug thread in a cylinder head. Then we would grab a prop blade and pull it up towards TDC on the compression stroke. A drop in indicated air pressure on an inline gauge would show the amount of compression drop and one listened for air escaping through the oil filler on the engine. Escaping air there indicated piston ring issues. Escaping air might also be heard at the carburettor or at the exhaust system. Valve issues were then apparent. If air was heard at all three points, it was natural to assume that cylinder, rings or valves needed reconditioning. All this was everyday work for us. One could get bored to tears doing ring or valve jobs but it paid for the rent on the hangar. We were not allowed to deal with crank issues. An engine with crank and bearing issues had to be sent off to a specialist establishment.

Most light aircraft fitted with Teledyne Continental, RR or Lycoming or other similar type engines would be subject to the above regime on a regular basis. Normal oil and filter changing would occur on a 50hr run basis or sooner if the "dummy at the front of the kite" reported engine issues. Whilst used engine oil would appear black when dropped, when on your hands (to be avoided due to hydro-carbon tissue impregnation...gloves not in common use in my day) would wipe off easily. Carbon contamination as a combustion by-product was not that heavy. Left to say 200hrs, then yes, it would have been much worse. In the case of the aircraft, oil was changed on a much more frequent basis than is common on a road going vehicle. Despite an engineers` best efforts, aircraft engines would wear MUCH more quickly than a road vehicle. The aircraft engines were in the main air cooled and of long stroke type. Piston speeds were high which further contributed to wear issues. Manufacturing tolerances were rather looser to keep friction and cooling issues within acceptable limits. Non of that helped with engine longevity in any way. Owners would have to expect to find themselves forking out for a refurbished engine on a regular basis. The SOAP test would help us with knowing how much longer an engine would last before needing replacement.

Wear is to be viewed as an exponential. A component will run for a time without any signs of wear down particulate being found by SOAP test. Once the signs appeared, one should expect to find dramatically increasing volumes of base materials being found on each test....wear never gets better...it only increases on a steepening curve. One minute the machine is ok, the next moment its worn out!

Expect the worst and you won`t be disappointed! Expect a machine to last for ever and you are living in cloud cuckoo land!! A SOAP test is a most useful test and lets you see inside an engine without having to tear it down

Mike K.

[AndyF]

Thanks Mike! I really enjoyed the background history on aviation and aero engine servicing.

I think my V12 will be fine for a while yet!

Andy

[ptjs1]

Andy,

Your results seem really good! Congrats!

I have had 2 kits ready to use for a year! Your post has prompted me to definitely do my 4 litre XJS on Wednesday.

I've deliberately waited to take the sample just before its oil change next week, so it will be interesting to see my results.

Paul

[AndyF]

Hi Paul

Did you ever get the 4.0 tested? What were the results?

Andy

[ptjs1]

Hi Andy,

Yes, sorry, I forgot to post back.

Really pleased with the results. Like yours, my figures seems really good on the face of it. Definitely something that I'll do on an annual basis from now on. I'd encourage everyone to get their engine oil analysed.

Cheers

Paul

[AndyF]

Hi Paul

Looks good! Plenty of life left in that one....

AF