A3 1.2 low oil pressure warning

[o_user]

3 hours ago, Magnet said:

Thanks Octavian,

OK, your 10w/40 oil is fully synthetic. Things probably vary from country to country then. 
I’m yet to see 10w/40 in the U.K. in anything other than semi-synthetic, or sometimes ambiguously marked  ‘synthetic technology’. 
Probably different in Romania. 
Kind regards,

Gareth. 

Hi Gareth,

 

I like your subtlety here. 🙂 On the box is written : Synthetic-based technology. ACEA A3/B4 - API SN/CF VW 501.01 / 505.00

[o_user]

2 hours ago, cliffcoggin said:

I have feeling that the discussion of viscosities etc. is a red herring in this instance, and that there is an underlying problem that has not been solved. Let me explain.

The oil pump should be capable of creating much more pressure than is required by the engine in order that the pressure is adequate at idling speed, no matter what viscosity of oil is used, any excess pressure as the engine speed rises being bled off by a pressure relief valve to maintain a more or less constant pressure in the oil galleries. In this case the pressure is not high enough to prevent the warning light showing, so the question becomes why that should be. The possibilities that occur to me are:

[1] The oil pump is worn.

[2] The pressure relief valve is faulty.

[3] The engine bearings are worn.

[4] The pressure switch is faulty.

[5] The pump is sucking in air.

Unless anybody can add to that list, or disprove my logic, the problem must be one of those five things. I know that some of those parts have been renewed, but even new parts can be faulty or incorrect for that particular vehicle. Furthermore I see no investigation reported yet of items [3] and [5].

What say you chaps?

Hi Cliff,

 

I guess I will never find out since is sold now but for what is worth. 

[1] The oil pump is worn. >>> it was generating pressure and if I remember good was 2.5bar at idle speed and close to 5bar al speed

[2] The pressure relief valve is faulty. >>>> not sure where this one is.... the oil filter and the oil filter house was replace with a new one

[3] The engine bearings are worn. >>>> Maybe

[4] The pressure switch is faulty. >>> I did replace it with a brand new one and made no difference

[5] The pump is sucking in air. >>> it was opened and checked 

But for sure somewhere was loosing pressure and now is not. 

P.S if I was driving with manual gear ( is automatic version) and I was changing the gears around 1.8k - 2k RPM the oil pressure light was not coming up anymore. As soon as I switch to automatic gear it will show the pressure light but only for a short period of time and then disappear. In automatic is changing gears at lower RPM then 1.7k

Best regards.

[Magnet]

Hello Octavian,

Well I think this debate boils down to:- ‘I’ve now passed the problem on to someone else’ ,and the response to the someone-else who complains in the near future that the oil light is coming might be along the lines of ‘well it wasn’t coming on when I sold it’!

For what it’s now worth, your ‘ NOT semi synthetic’ is unfortunately not what it seems. ‘Synthetic technology’ is the marketing executive’s terminology for convincing a potential buyer (your self in this case) that the oil he is buying is fully synthetic, when it’s actually not - it’s semi synthetic. 

Still, water under the bridge hey...

Kind regards, 

Gareth. 

[Stevey Y]

Hi the difference between 5w-30 and 10w-40 are minimal as the flow/viscosity rates are pretty much the same when starting, BTW the w denotes winter, where the 40 scores more highly is in the upper temperature conditions as its viscosity remains constant up to 50 degrees Celsius where the 30 is only good up to 30 degrees celsius. therefore if you do a lot of town or fast driving the 40 is the better option as it gives better protection for the engine components that are under higher thermal stress, where as the 30 will not.

Zero 30-40 oils were developed for the high performance market where engineering tolerances between crank journals and pistons are a lot finer than in standard cars therefore instant oil pressure is essential when cranking to prevent bearing knock, its all about the additives that are put in friction modifiers, molecular stabilisers, viscosity stabilisers, each oil has to pass within the modules used to test the quality and the results are passed on to trading standards so if there is ever a problem with the manufacturers oil the manufacturer can rely on those figures to produce the evidence that their product is good enough.

Couple of years ago I went to a local oil additives manufacturers open day with a mate of mine who worked for Ford, when we arrived the first demonstration was with two identical engines in test cells, one was filled with oil straight from the refinery with no additives the other engine was filled with Sainsbury's oil, they were both started and within three minutes the engine with no additives seized solid whilst the other was running quite happily, we were shown what happens when oil overheats and by the end of it we were in a lecture theatre being shown all about pass rates on test modules, these are governed by the brands requirements and looking through who had the highest pass rates it made shocking reading the top five pass rates were Mobil, Millers, Fuchs and Sainsbury's who had demanded the highest pass rates in each module, some such as Castrol, Halfords, Asda, and good few others were way down the ratings as they had asked for lower pass rates to keep it cheaper to produce, its the additives that cost the money.

10w-40 is not a lot thicker than 5w-30 its in the temperature ratings at the top end that are the main difference 

Regards Steve.