Oil Pressure drops :(

[Supracentral]

How about illogical?

He got his point across - don't drag this thread off topic grammar nazi...

I guess I'd better just come out and say what you already suspect. I am fairly new to all of this. I've done minor work to my car with the help of more knowledgeable people.

I'm right about due for an oil change. The car has 111,000 miles on mostly original parts. My last oil change was maybe 108,500. Unfortanutely I live in an apartment and don't have my own garage so I used a shop to change my oil last time. I don't know what brand/weight was used. It just recently had the head gasket replaced but it's got a lot of old hoses I've been replacing. The guy that owned it before me kept it very nice in a climate controlled garage in New York.

I didn't have my head on straight when I first got this car. I was always under the "drive it like it was meant to be driven" mentality and didn't take the best care of my car during the first two years. I've since rethought everything and have been trying to take it easy. Trying not to drive it into the ground. I'm trying to do most of the maintenance myself but I live in an apartment and do not own my own garage. It's difficult for me to get anything done in the Florida heat .

There are a couple things currently wrong. The engine has a slight hesitation that I'm told is due to an intake leak. I replaced the hoses from the MAF to the turbo/throttle body... but I still can't find it. The turbo hesitates a little as well probably due to the same problem. The clutch is starting to slip and of course the oil pressure problem.

Sorry for the essay but I thought it might help to better understand the idiot you're dealing with

Ok, so we've got:

When was the last oil change (how long / how many miles ago)? 2500 miles
What oil was used? Unknown
What filter? Unknown
What's the age of the engine? 111,000 miles
What's the overall mechanical condition? Good
Any ideas on how this car has been maintained over the years? Sounds like it was well maintained, but suffered about 2 years of "hard use"

With all that said, #1 - eliminate the unknowns.

Choose a good oil. This will help:

http://www.supramania.com/forums/showpost.php?p=533980&postcount=1

Keep in mind where you drive the car. If you stay 100% in Florida, you can work with slightly thicker (German Castrol 5w-30) oils. If in doubt, ask Jdub for a specific recommendation. I'm going to shoot him a link to this thread to double check me here.

Don't be afraid to switch to synthetic oil (that first link will tell you what synthetic oil is an isn't):

http://www.supramania.com/forums/showthread.php?t=49245

Run one quart over the full mark on the dipstick. (This is usually 6 -/+ quarts in the 7M-GTE)

Use a good filter:

http://www.supramania.com/forums/showpost.php?p=589060&postcount=2

Personally I'd suggest a Wix or Purolator PureOne

Once you have those things settled, you are on firm footing. You know what you have, and our ability to respond to you will be enhanced quite a bit.

Overall, from what you're describing, there may not be anything wrong with your oiling system other than normal 100K wear.

How recent was the head gasket change?

Address the unmetered air leak. It shouldn't be that hard to find/fix. That can cause detonation, which can put you right back in blown head gasket land.

 

[rayall01]

He got his point across - don't drag this thread off topic grammar nazi...

Who, ME?:naughty:

 

[wizeguy707]

Don't fret about the oil pressure though. I've had my 87' for a year and a half now. It does the same kind of oil reading, even a little worse in this Texas heat(idling around 15-18psi). I've put 6392 miles on her:aigo:, and she still runs like a champ. Just don't let one of these shops put a light oil in your ride. Then your problems may errupt from there. I stick to 20-50.

 

[jdub]

Cobbeh - SupraCentral pretty much covered it...you have a bit of reading to do.
I like Castrol European Formula 0W-30...it says "Made in Germany" on the back (aka - German Castrol). Don't make the assumption this is a thin oil...at ops temp it is one of the thickest there is for a 30W multigrade at ops temp.

Don't fret about the oil pressure though. I've had my 87' for a year and a half now. It does the same kind of oil reading, even a little worse in this Texas heat(idling around 15-18psi). I've put 6392 miles on her:aigo:, and she still runs like a champ. Just don't let one of these shops put a light oil in your ride. Then your problems may errupt from there. I stick to 20-50.

You have no clue what you're talking about...running a 20W-50 one of the worst things you can do to your motor besides driving it with a known blown head gasket. Looks like another case of "well my mechanic told me or I heard"...the supposed "benefit" of running a thick oil is a myth.

The high viscosity in the 50W multigrades flows like honey when cold...that is very bad for open bearings (like the rod and mains). You want to run an oil with the lowest 1st number you can get in a 30W multigrade (i.e. a 0W or 5W-30). The 7M was designed to run a 30W viscosity at ops temp (100 deg C)...it covers almost all conditions a stock to moderate modified car will encounter.

Why don't you read the Motor oil 101 link in my sig...you really need to based on the above statement. Might want to STFU about oil till you figure out what you're talking about.

 

[cobbeh]

Cobbeh - SupraCentral pretty much covered it...you have a bit of reading to do.
I like Castrol European Formula 0W-30...it says "Made in Germany" on the back (aka - German Castrol). Don't make the assumption this is a thin oil...at ops temp it is one of the thickest there is for a 30W multigrade at ops temp.




You have no clue what you're talking about...running a 20W-50 one of the worst things you can do to your motor besides driving it with a known blown head gasket. Looks like another case of "well my mechanic told me or I heard"...the supposed "benefit" of running a thick oil is a myth.

The high viscosity in the 50W multigrades flows like honey when cold...that is very bad for open bearings (like the rod and mains). You want to run an oil with the lowest 1st number you can get in a 30W multigrade (i.e. a 0W or 5W-30). The 7M was designed to run a 30W viscosity at ops temp (100 deg C)...it covers almost all conditions a stock to moderate modified car will encounter.

Why don't you read the Motor oil 101 link in my sig...you really need to based on the above statement. Might want to STFU about oil till you figure out what you're talking about.

Alright, I've read the Motor oil 101 link you gave (and kept going to 109) and I have a question. You recommended a 0W-30 oil. From what I've gathered the first number tells me the viscosity of the oil while the engine is cold and the second is the viscosity when it's hot. If I have an oil pump that could be on it's way out the door or a slight pressure problem when running hot... shouldn't I try to use an oil with a higher second number? More viscosity in the oil would help to increase oil pressure right?

Sorry if I sound like an idiot. I did read it, I'm just not sure if I fully understand it.

10psi per 1000 is the maximum not driving at 3000=30 psi....

I'd expect to see at least 40psi @3000 in a healthy engine but having said that the "Shop" is full of shit and trying to take your $900....

One more stupid question and I'm done.. I swear.. according to the above quote.. if I was running say 90+ miles an hour at 4000 rpms... would I expect to see around 40 psi of pressure? If I ran at 100+ on the highway at 4000+ rpms and it never went above the low 30's psi would that be a bad thing?

I truly am grateful for all the help and advice everyone has given so far. I'm going to go get the oil changed tomorrow to the 0W-30 you recommend which I believe is found at auto-zone? I'm also going to see if I can't narrow down the vacuum leak before my car blows up.

 

[rayall01]

Don't fret about the oil pressure though. I've had my 87' for a year and a half now. It does the same kind of oil reading, even a little worse in this Texas heat(idling around 15-18psi). I've put 6392 miles on her:aigo:, and she still runs like a champ. Just don't let one of these shops put a light oil in your ride. Then your problems may errupt from there. I stick to 20-50.

Yeah, listen to jdub, and learn!

 

[IJ.]

10psi per 1000 rpm is the maximum you shoot for so if you were running an engine to 8000 red line you'd shoot for a hot Oil pressure at 8000 of 80 psi, the same engine may make 80 psi at 5000 as well.

The stock GTE oiling system has so many controlled leaks it's hard to get it to make more than 40 psi until you're revving it quite hard and the pump is flowing enough to fill the leaks.

Usually if you're steady state cruising you'll see pressure rise in time as the Cooler opens cools the oil and it thickens slightly, not sure how noticable this is on a stock gauge but it's very apparent on my MoTeC dash.

 

[dumbo]

Alright, I've read the Motor oil 101 link you gave (and kept going to 109) and I have a question. You recommended a 0W-30 oil. From what I've gathered the first number tells me the viscosity of the oil while the engine is cold and the second is the viscosity when it's hot. If I have an oil pump that could be on it's way out the door or a slight pressure problem when running hot... shouldn't I try to use an oil with a higher second number? More viscosity in the oil would help to increase oil pressure right?

Sorry if I sound like an idiot. I did read it, I'm just not sure if I fully understand it.

Higher viscosity will give you higher pressure, but will likely lower the flow to the parts of the engine that need the oil. Pressure is caused by resistance to flow after all. jdub may shoot me down for those comments but thats how I see it. With that being said I switch from 10-30 to GC 0-30, mainly due to his write-ups. And I despise synthetic oils, but I got them in my tranny and engine...I hope you right jdub haha.:biglaugh:

 

[deabionni]

Alright, I've read the Motor oil 101 link you gave (and kept going to 109) and I have a question. You recommended a 0W-30 oil. From what I've gathered the first number tells me the viscosity of the oil while the engine is cold and the second is the viscosity when it's hot. If I have an oil pump that could be on it's way out the door or a slight pressure problem when running hot... shouldn't I try to use an oil with a higher second number?

I like Castrol European Formula 0W-30...it says "Made in Germany" on the back (aka - German Castrol). Don't make the assumption this is a thin oil...at ops temp it is one of the thickest there is for a 30W multigrade at ops temp.

Check out this post by jdub. German Castrol is almost as thick as a 40 weight oil at operating temperature.

 

[jdub]

Alright, I've read the Motor oil 101 link you gave (and kept going to 109) and I have a question. You recommended a 0W-30 oil. From what I've gathered the first number tells me the viscosity of the oil while the engine is cold and the second is the viscosity when it's hot. If I have an oil pump that could be on it's way out the door or a slight pressure problem when running hot... shouldn't I try to use an oil with a higher second number? More viscosity in the oil would help to increase oil pressure right?

Sorry if I sound like an idiot. I did read it, I'm just not sure if I fully understand it.

As mentioned, you need to focus on flow vs pressure...as long as pressure is within TSRM limits, you have all the pressure you need on a stock motor. If the oil pump is providing the TSRM pressure, you don't need to worry about it.

Pay attention to the above post by deabionni...GC is not a thin oil by any means at ops temp. It's one of the mistakes folks make, they see the "0W" and assume it's a thin oil...not the case. It's the actual viscosity at opts temp that matters. Every company publishes data sheets on the oil they sell...both cold and hot viscosities are listed. A smart guy would pay attention to those numbers

One more stupid question and I'm done.. I swear.. according to the above quote.. if I was running say 90+ miles an hour at 4000 rpms... would I expect to see around 40 psi of pressure? If I ran at 100+ on the highway at 4000+ rpms and it never went above the low 30's psi would that be a bad thing?

I truly am grateful for all the help and advice everyone has given so far. I'm going to go get the oil changed tomorrow to the 0W-30 you recommend which I believe is found at auto-zone? I'm also going to see if I can't narrow down the vacuum leak before my car blows up.

It is at Autozone...PepBoys has it as well. Make sure it is the European Formula and says "Made in Germany" on the back.

IJ nailed it concerning higher RPM pressure on the following post:

10psi per 1000 rpm is the maximum you shoot for so if you were running an engine to 8000 red line you'd shoot for a hot Oil pressure at 8000 of 80 psi, the same engine may make 80 psi at 5000 as well.

The stock GTE oiling system has so many controlled leaks it's hard to get it to make more than 40 psi until you're revving it quite hard and the pump is flowing enough to fill the leaks.

Usually if you're steady state cruising you'll see pressure rise in time as the Cooler opens cools the oil and it thickens slightly, not sure how noticable this is on a stock gauge but it's very apparent on my MoTeC dash.

Here's a couple exmples of the "controlled leaks" IJ speaks of:
- Oil squirters on the GTE engine open at ~40 psi
- Stock cooler circuit relief valve also opens up at ~40 psi, routes oil to the cooler, then dumps it straight to the pan. Contribites zero flow to the block as a result.

Both of these pretty much limit the top pressure on a stock motor to 40 psi or slightly above. On a rebuild, you can shim the oil pump relief valve ~5mm and gain 20 psi of pressure. I would also replace the squirter bolts...if they have a lot of miles, it is pretty common for them to open early and make the pressure bleed worse. One of the best upgrades to the oil system IMO (without getting into the block) is to install a full flow, thermostat controlled cooler circuit...eliminates at least one "leak" fairly easily. The how to is located in the stickies in the Lube Section.

Higher viscosity will give you higher pressure, but will likely lower the flow to the parts of the engine that need the oil. Pressure is caused by resistance to flow after all. jdub may shoot me down for those comments but thats how I see it. With that being said I switch from 10-30 to GC 0-30, mainly due to his write-ups. And I despise synthetic oils, but I got them in my tranny and engine...I hope you right jdub haha.:biglaugh:

Close enough
Thicker oil on a stock system is not what you want. A synthetic (PAO or ester) is what you want...it takes the heat generated by a turbo motor without break down.

 

[cobbeh]

As mentioned, you need to focus on flow vs pressure...as long as pressure is within TSRM limits, you have all the pressure you need on a stock motor. If the oil pump is providing the TSRM pressure, you don't need to worry about it.

Pay attention to the above post by deabionni...GC is not a thin oil by any means at ops temp. It's one of the mistakes folks make, they see the "0W" and assume it's a thin oil...not the case. It's the actual viscosity at opts temp that matters. Every company publishes data sheets on the oil they sell...both cold and hot viscosities are listed. A smart guy would pay attention to those numbers



It is at Autozone...PepBoys has it as well. Make sure it is the European Formula and says "Made in Germany" on the back.

IJ nailed it concerning higher RPM pressure on the following post:



Here's a couple exmples of the "controlled leaks" IJ speaks of:
- Oil squirters on the GTE engine open at ~40 psi
- Stock cooler circuit relief valve also opens up at ~40 psi, routes oil to the cooler, then dumps it straight to the pan. Contribites zero flow to the block as a result.

Both of these pretty much limit the top pressure on a stock motor to 40 psi or slightly above. On a rebuild, you can shim the oil pump relief valve ~5mm and gain 20 psi of pressure. I would also replace the squirter bolts...if they have a lot of miles, it is pretty common for them to open early and make the pressure bleed worse. One of the best upgrades to the oil system IMO (without getting into the block) is to install a full flow, thermostat controlled cooler circuit...eliminates at least one "leak" fairly easily. The how to is located in the stickies in the Lube Section.



Close enough
Thicker oil on a stock system is not what you want. A synthetic (PAO or ester) is what you want...it takes the heat generated by a turbo motor without break down.

I understand and thanks again. I went and bought the oil you recommended today and the Napa Gold oil filter. Going to do the oil change myself tomorrow or Friday and see what happens

 

[jdub]

I think you will be pleased with the way that oil performs
It will last 8,000 miles easily...I would change the filter at 4K though and add make-up oil.

If anyone hasn't told you, you want to fill a quart above the top mark on the dipstick...call it insurance.