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.

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

13 minutes ago, Magnet said:

Many thanks Steve. Thanks goodness for the facility to have a free interchange of opinions. 
If we revert to Octavian’s issue of an apparent low oil pressure when using the correct specified oil viscosity, and his now satisfaction that the issue has been resolved by using a higher viscosity, is really akin to potentially adding ‘treacle’! until the ‘thicker’ oil holds its viscosity for some temporary period, and to some extent. How long?? 
Personally, I fear this will prove to be a short term dodge, but......

Re. semi synthetic vs fully synthetic? Of course, there are schools of thought that maintain oil-is-oil-is-oil, and that to spend any additional funds on recognised brands is simply financing the brand name, and equates to a waste of money. Maybe so and opinions vary. For what it’s worth, my opinion rests (with DIY) by buying the ‘apparent best’ at most competitive prices, since my labour is cheap! - but I always stick with the recommended specifications - I simply don’t see any benefits in deviating. This equates to using fully synthetic if fully synthetic is specified, or indeed semi synthetic where that is specified, and even straight mono grades in vehicles which are as old as me! I base this on my lack of in-depth knowledge of oil manufacture, despite being from a technical background, so I see no reason to challenge those who design engines and those who recommend the lubrication specifications for them.

 
Back to Octavian:- I would still stick with my suggestion of using fully synthetic 5w/40 if he feels he is prepared to mask possible underlying issues by moving from 5w/30, and can only add that there is a strong possibility that the fully synthetic variant will most likely ‘hold its viscosity’ longer than his semi-synthetic variant, resulting in him masking the issue for longer. Is the slight additional cost of using a fully synthetic rather than a semi synthetic worth the extra? 
Many thanks again Steve,

Kind regards,

Gareth. 

 

Hi Gareth,

I totally understand this but please note that the oil I have put is synthetic and  NOT semi-synthetic and is for my type of petrol engine. Also I know that after 100k Km the viscosity of the oil should increase to accommodate for the wearing out of the parts ( correct?!) . I don't think you can stick with the same 5W30 until the end of lifetime of any engine, unless you change some of the inner parts. 

Kind regards.

Hi,

Just a small mention to my last post.. the oil that I have put was Motul and not Motion. Anyway, the problem was fixed not by replacing the oil pressure sensor that was also changed with a new original one and was resolved by changing for a third time the oil from 5W30 to 10W40.

All the best and thank you for support. 

Hello guys. 

So the work done by the mechanic was as fallows: he clean the engine with a solution that he added in the oil, he verified the pressure of the oil, he cleaned the oil pan and check the oil pomp. He found that inside the oil filter house the pressure valve was missing so a new one was put ( the previous maintenance was done wrong and the mechanic from there throw it away 🤬). Oil was change from Castrol to Motion 5w30 and a new filter. He also checked the oil sensor pressure, clean it and put it back. Today I had to leave from the city were this was made and getting back to my busy home city and the oil pressure gauge got lit. I have call back the mechanic and he said that maybe the oil pressure sensor is causing this. I will see now change this sensor. I feel sorry that I didn't change together with the everything else. 

I need to sell this car 😂😂... 

29 minutes ago, cliffcoggin said:

Octavian.

You have used a decent quality oil so there is no point wasting money by changing it again. Your problem lies elsewhere.

Hi.

Due to my working hours and not being able to find a decent place to do the replacing of the sensor and oil filter on the spot and long waiting hours, I have decided to give it to some mechanic that will, according to him, clean the system, oil pump and all the components and verify if they are damaged plus the pressure test.

It will be done next week and I'll get back with what he found. 

Best regards,

Octavian

Thank you for the reply Gareth.

I will go ahead and replace the oil pressure sensor and the oil filter but not in the same time so I can pinpoint the culprit. If this doesn't solve it I will change the oil with a different brand. 

Best regards,

Octavian

On 4/11/2019 at 10:42 PM, chrisjpearson84 said:

Thank you very much for your advice I’m getting my car looked at so will soon know what’s wrong thank you 

Hi Chris.

What was the fix in your case?

Hello guys,

i have a similar problem with my A3 2.0 TFSI 2005 model (156000Km). I have just changed the oil and the filter and when the engine temperature gets to the optimal running temperature 90*C at around 1600rpm( coincidence) i get the same oil pressure warning light. I have measured the oil pressure but when temperature was low and i had 2.6bar / close to 40PSI at idle speed and at 2000-3000rpm i had 5bar and a bit/ 80psi. Also the oil pressure sensor had a bad wire that according to the mechanic was fixed. The light stays lid for a short period of time (less then a minute) and disappears, but not for long as comes back again and again at random times. Can it be because of bad oil quality Castrol Edge 5W30 LL or the sensor or maybe something else at the engine? No visible leaks found.