Q: When should I change my engine oil ?



Source.

This post has been edited by zeng: Aug 25 2019, 11:29 PM

Upload on behalf of a friends of mine wish to know the condition of the oil

Mercedes Benz S600 6.0 V12 year 1994
Bought over from owner and previously car sit in the garage over a year before tow back to workshop for repair and service
Oil use : Shell Helix HX3 20w50
Oil mileage: roughly 400Km
Odo meter : unknown as meter spoiled

This post has been edited by 90Boyz: Aug 26 2019, 10:21 AM

Hi,
Short answer:Tell your friend this 400 km oil is good and fit for continuing service.
Long answer will come after some readings on S600 and history of API/ACEA then.
Btw, exactly what mechanical repair/service was done ? or just replace engine oils only ?

This post has been edited by zeng: Aug 26 2019, 03:59 PM

Hi Zeng bro,
Appreciate the explanations ..
repair/service : to replace faulty fuel pump and 12pcs of spark plugs .. other than that, everything basically untouched.

This 1994 MB S600 6.0L V12 is a W140 carrying an M120 engine with port fuel injection system.

A bit of history , back in USA the API SH (obsolete) was launched in 1993 whilst SJ was launched in 1996.

In Malaysia ,this MB S600 would have called for SH (which wasn't available in Malaysia until probably 1995/1996) or SG which was available beyond 1994.

Recommended OCI (oil change interval in km) back then had always been 5,000 km for our local petrol with sulphur content of around 10,000 or more ppm (parts per million of Sulphur in petrol) .
However, this MB S600 was likely imported European version into Malaysia as used car.

In Europe, it likely called for European spec CCMC G4 or G5 petrol engine oils whose specs is over and above that of API SH.
This engine probably called for similar oci of 5,000 km with pre-Euro 1 petrol of sulphur content around 5,000 ppm in Europe then.

Now, this Shell HX3 20W50 API SL far exceeds the original API SG/SH specifications requirements of MB back in 1994 and bearing in mind that currently available Malaysian petrol is more superior and cleaner at Euro II (500 ppm Sulphur) or Euro VI (50 ppm sulphur) petroleum standards, I'm of the opinion its oil change interval OCI should be good for 5000 km or likely more, assuming a reasonably maintained engine condition.

Now, coming back to your blotter spot.

In relations to other blotter spot pictures at Post #1 , this 400 km usage HX3 20W50 engine oil is a bit on the 'dirty' side as demonstrated by its darker shades of soot/byproducts of combustion and oxidation within the intermediate diffusion zone.

Is it due to poor engine oil quality or 'dirty' engine internals ? IDK for now but it likely could be both, who knows.

However upcoming blotter spot tests on this oil probably could tell us something more as we progress from here .

The good news now is that the dirt/byproducts/soot is of small size, small quantity and light enough to be carried by the oil far away from the centre/deposit zone into the external diffusion zone . This indicates oil oxidation is not serious enough and its detergency and dispersancy capabilities are still in tip top condition and hence this used oil is fit for continuing service, IMHO.

It also shows absence of fuel dilution problem , probably all 12 fuel injectors are working normally with a new fuel pump in place. The blotter also shows absence of coolant/glycol problem in the engine.

You may need to check with your friend about his comfortable oil change interval. Assuming a tentative OCI of 5000 km, I wish to suggest taking a blotter spot test at every 1,000 km interval from now on for evaluation/comparison of used oil conditions , until say km 4000/4500 with a view of making a final decision then whether to proceed with replacement of this HX3 20W50 sample at 5,000 km as intended.

Just my 2 sen.

Edit:Your friend should seriously consider MB-approval oils in future, not oil spec'ed in API only.

This post has been edited by zeng: Aug 27 2019, 03:02 PM

Many thanks for the ultra detail explanations .
will advise my friend on the OCI interval
one problem he encountered that he smell the petrol fumes from the exhaust suspect the engine was burning "rich "
he soon will visit the MB specialist to check on the spark plug condition to determine the conditions..
also will take another blotter spot test after reaching 1000km mark.
thanks again.

This post has been edited by 90Boyz: Aug 27 2019, 03:12 PM

Hi 90Boyz,

Whilst petrol fumes from exhaust may indicate 'rich' burning, this 400 km blotter doesn't indicate fuel dilution IMO.

As owner ,I would walk away to others if this 'MB specialist' recommends me fuel injectors replacement.

Btw, what was the basis/reasons for fuel pump replacement previously ? Difficult 'starting' after 1 year idle may be helped with injector service rather than fuel pump replacement , hence it should not be the reason leading to fuel pump replacement , IME.

Generally fumes could be caused by leaks at fuel tank accessories, fuel line joints , improper reassembly of joints during fuel pump replacement job , hardened injector seals (once it was 'touched by injector disassembly' during previous fuel pump job) etc.

Edit:Meanwhile consider temporary use of 'fuel injector cleaners' , and select BHP RON 95 petrol for its '800 ppm' fuel additives content.
No, this car doesn't need RON 97 whether or not it's a fuel guzzler but I suppose your friend could afford it.

This post has been edited by zeng: Aug 28 2019, 01:34 PM

Oops, may need to do some research on MB 229.3 that's suitable and relevant for a 1994 Mercedes-Benz S600 6.0L V12 petrol port injection engine whose Shell HX3 20W50 SL (without MB 229.1/229.3) blotter spot is as above.

It's M120 engine doesn't quite need the extended interval MB 229.5 oils.

noted on the comment, he will send his W140 to check on the injector seal's conditions and make sure all injector are in working conditions and meanwhile he is using 3M fuel injector cleaner combo with BHP Ron95 as per advise.

This post has been edited by 90Boyz: Aug 29 2019, 12:58 PM

Don't forget the petrol filter, look into the cheaper parts 1st before going into more expensive components.

It is a good idea to replace the cheapo fuel filter in such an old age car whose maintenance history may be quite 'unknown' to new owner.
Having said that, I believe a malfunction or blocked fuel filter should not cause petrol smells in exhaust fumes.

yup, the fuel filter are changed along with fuel pump.

Has come across an M1 EP 5W30 UOA at 12000 miles (not km) on Bitog and it performed very well.

Will see if I'm able to trace the UOA on Bitog and upload here accordingly for the benefit of readers .

Btw, MI EP 5W30 has 20-30 % Group IV Poly Alpha Olefins (PAO) base oil.



This post has been edited by zeng: Aug 31 2019, 11:58 AM

Wow, Quite a surprise it has PAO for the EP. Looks positive as I will look forward to continue using this engine oil in many oil change to come. I do have thought of switching to other oils but since this EP exceeds much. Will just use this oil instead.

Hi @zeng
Could you spare some time to evaluate this 48 hr blotter spot?
Thank you Sir.

EO: Mannol Diesel Extra 10W40 CH-4/SL
Engine: Nissan GA16 Carburetor
Odo: 305584 km
EO mileage: 8325 km
Usage condition: 95% stop/go traffic in town, 4-5 times start-stop daily


Attached thumbnail(s)

Hi Chemistry, thank you for sharing the blotter spot test of a HDEO Mannol Diesel Extra 10W40 CH-4/SL semi synthetic .

Usage condition of 95% stop/go in town and 4-5 times daily start-stop would be considered by all if not most vehicle OEM's as severe service, cutting its normal OCI to half typically.

What more we are talking about an oldie carburretter engine that typically calls for short OCI in the good old days.

Having said that this 8325 km oil is traditionally considered as 'too' long an OCI for a carburretter engine but you know what, this used oil is fit for continuing service basing on the following:

a) this oil is dispersing the soots/dirt/contaminates away from deposit spot very well, though it's graying/darkish colour indicates quite an amount of soot/dirt etc ;
b) there is absence of 'emergence' of centre zone;
c) there is absence of structures/rings/halos on blotter spot;
d) there is quite an indication of fuel dilution, probably inherent in a typical carburretter engine but , it's not a big deal really.



According to the following picture, I would rank or classify your blotter spot condition as good sitting in between Spot 1 and Spot 2.

These pictures advise only planning/scheduling an oil change AFTER this oil has further worsened/deteriorated to Spot 7 ......
it remains an advice though , as all of us would get freak-out here.




Source

This post has been edited by zeng: Sep 1 2019, 12:16 PM

Thank you so much, @zeng , for sharing invaluable insights.
I think I'm going to stretch to 10,000km then only drain it out. 10k is enough already, considering the oil has been in service since 1-Sep-2018. Initially I planned to change oil in this week.

This blotter spot test of yours demonstrates engine oil life of today is quite independent of, or not quite influenced/dictated by :
a )fuel dilution, arising from carburretter engine , and
b )12 month usage limitation of engine oil, which does not lead to 'automatic' condemnation of oil.

The above 'conclusions' are also being backed up by numerous Used Oil Analyses.

IME, your suggested 10,000 km OCI is likely to be a non-issue in terms of used oil quality.

This post has been edited by zeng: Sep 2 2019, 10:57 PM

so this is about a week plus after applying seafoam. i think its a 72 hours pic after taking sample


and this is after 2 days change out the seafoam, with giant shell helix hx8 5w30 SL.
changed the filter as well. i believe this is also 72 hours pic after taking sample



from pic, it seems like i dont need to change the oil again (sacrificial oil) after changing out seafoam, seems pretty clear to me.
but its weird that this sample oil is gray rather than usual brown color.

but this is also first time i use this oil.

all this while using 5w30, changed to 5w40 on jan, switched back to 5w30 now, feel back the smoothness. but...i do feel like its smoother from my feel using 5w30 previously.
so it could be seafoam is really working.

Hi Bro,

This a-week plus after seafoam blotter spot looks less grayish, hence cleaner than your previous two-day after seafoam blotter spot below,

.... this presents confusion as to 'why' the inconsistencies in blotter picture appearance/display that could be explained by variations in circumstantial factors , back lighting etc between the two occassions on blotter taking.

But, one thing remains valid is the supposed 'increase' in dirt/soot/contaminants or dispersancy breakdown after one-week plus seafoam usage has not caused rapid oil deterioration to 'destroy' this HGEO 0W30 to the extent that it warrants 'so soon' a removal or replacement as advised by seafoam factory/experts.


Comparing this 2-day usage blotter spot of yours against another HX8 5W30 SL 1069 km blotter of 90Boyz several posts above, the 2 day usage blotter (after changing out seafoam'ed HGEO 0W30) demonstrate observable graying dirt/soot etc . Would the blotter darkened further ? Possibly.
Btw, I'm equally surprised at absence of yellowish/brownish coloured blotter spot appearance , as normally observed.

But at this stage of blotter appearance, I'm of the opinion this HX8 doesn't warrant immediate replacement as 'sacrificial' oil , yet. Instead it may be construed as wasteful, as far as residual oil qualities is concerned.

As regards, attributing smoothness feel etc upon oil replacement to having seafoam'ed is , IMHO, a placebo effect I speculate , unless and until this seafoam left behind adequate amounts of Moly ,Titanium and/or Boron additives after oil change, which it did not purport to claim .

This post has been edited by zeng: Sep 5 2019, 02:10 PM