Dino 10W40 ----> AMS 5W40 oil pressure drop

[Pablo]

"It is a waste to drain the brand new AMSOIL after using it for 2 days. I am thinking of removing 500ml and replacing it with 20W50. It may increase the viscosity just enough to stop the dummy light." Agree, maybe a wise move, but may take a full liter. Since you have acceptable pressure at higher RPM's my theory is pretty much confirmed.

 

[friendly_jacek]

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Originally posted by Pablo: "It is a waste to drain the brand new AMSOIL after using it for 2 days. I am thinking of removing 500ml and replacing it with 20W50. It may increase the viscosity just enough to stop the dummy light." Agree, maybe a wise move, but may take a full liter. Since you have acceptable pressure at higher RPM's my theory is pretty much confirmed.

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I thought that oil pressure light flickering was consider normal in some high mileage european cars. IMO, this whole thing suggest to me that this particular synthetic oil does not work well for your car. I would do 50/50 mix with 20W50/15W50, especially for summer driving. You can always save the drained almost new oil and reuse it later. FYI, in my boat, I did a switch from dino 40 to synthetic 5W40 and observed no difference in oil pressure. The oil is not amsoil and the engine is low-hours though.

 

[Lumberg]

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Originally posted by kickster:

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What was the pressure at 2K, 3K, etc RPM? - this is more important.

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Pressure is @ 1.8 Bar (1900 rpm) 2.0 bar (2200 rpm) 2.5-3.0 Bar (3000 rpm) 3.0+ above 4000 rpm. The pressure is high while driving. It only goes low at idle! It is a waste to drain the brand new AMSOIL after using it for 2 days. I am thinking of removing 500ml and replacing it with 20W50. It may increase the viscosity just enough to stop the dummy light. [/QB]

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You might want to try an oil thickening additive like motor honey or something, just as a stopgap measure to keep using this oil. Obviously it is important to get the light to turn off, cos you need to know when your oil pressure is REALLY low, like when there's a leak or a spun bearing or whatever. Another option would be to drain it and save it. Refill with something thicker, then for the next OC make up whatever didn't come out (like what's left in the filter) with something really thick like a 20-50 like you said, then after that use a 10-40 or whatever. I would also like to clarify if it's the oil presuure while hot that is the problem. If that's the case maybe you should try a 5w50 oil so you don't sacrifice as much of the low-temp flow characteristics as fwith going to a 10w oil.

 

[kickster]

5W40 is AMS's european formula and on the back it says VW approved. I thought it should work fine! this car ran fine even with dino 10W30 during winter time!

 

[Mike_dup1]

Ever think that maybe the oil pressure sensor is in need of replacing? My 1992 truck would show very low oil pressure at the gage but when the idle was increased a few 100 rpm, it would jump up and would be good at cruise. Installed a new oil pressure gag sensor and no more problem. These often can get gummed up over many miles such as you have accrued.

 

[Pablo]

Kickster - I know you struggle with this but the name of the company is Amsoil. Not AMS. You are welcome to try other synthetic oils, but I bet any other synthetic 5W-X will have the same issue. Have you considered a synthetic 20W-50? [ June 15, 2004, 05:14 PM: Message edited by: Pablo ]

 

[Cary]

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Originally posted by Dr. T: Well, guess you witnessed that the 5-40 is definatetly thinner than the 10-40. Firstly, probably because it's a 5W rather than a 10W (as in 10W-40) or 15W (as in a 15W-40). Secondly, it's a synthetic. The particles are more uniform and the oil flows better than the comparable dino oil. If it's an issue with the oil light (and it would pi$$ me off too), just switch to the AMS 10-40....

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Dr T, I am dissapointed in you. We all know that the Xw of an oil has nothing to do with its thickness at operating tempurature. The problem here is at operating temp, where the oil is approximately 14.5 cst. Cary

 

[moribundman]

Both my VW cars (Scirocco Mark I and Mark II) had oil pressure senders go bad. That's where I'd look before blaming the oil. I've also had the oil pump go bad. The motor really shouldn't be clapped out at that mileage. Valve stem seals have probably been replaced once? [ June 15, 2004, 06:26 PM: Message edited by: moribundman ]

 

[kickster]

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You are welcome to try other synthetic oils, but I bet any other synthetic 5W-X will have the same issue. Have you considered a synthetic 20W-50? [/QB]

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I am not trying to beat on AMS (AMSOIL I have been using AMSOIL 10W40 and 20W50 in my other VW (same age) for long time with no problem. However the other VW has always been treated with synthetic oil. I am going to try another sender and see if it works any differently.

 

[kickster]

I think the problem is the sender unit. I just replaced it with another one and dummy light doesnt come on. I have 2 used senders and light wont come on with either one of them. Just to be sure I will try to find a mechanical gauge and see what the readings say.

 

[Pablo]

OK I was confused....I thought you had tried a mechanical gage. Oh well!