Low Oil Pressure

[Nat3dog]

Let me give a quick history on my bucket. It was a father son project that was finished back in 2010. It has sat in the garage since 2010 and just started once a month to make sure nothing freezes up. I ended up trading my 350Z to the kid for the bucket. I had it delivered to my house last Thursday and started driving it around my neighborhood just to make sure every thing was working right. I had to fix a few little things here and there but nothing big just normal stuff for it sitting so long. Now on with my real problem I am having. I noticed yesterday while I was driving around my oil pressure was staying low between 0 and 20 psi. When I gave it gas it would go up to the middle but when stopped at a light it would go way down. The car drives fine and is not getting hot or making any funny noises. I figure today I will do an oil change on it and see if that helps. It might just be a faulty gauge but not sure yet. My question is what else should I check?

 

[Mike]

Small block Chevy? If so, 20 lbs. at idle is naught to be real concerned over. So long as pressure goes up as engine RPMs increase. What kind of oil pressure gauge do you have, electrical or mechanical?

Yuo might check the dipstick before you change the oil, to be sure the level is OK. Be sure to refill with the proper quantity of oil, when you do your change. Then keep an eye on things, after the change.

 

[Screaming Metal]

I see you've met our Reverend Mike. He speaks all things HotRod, and blesses us with Wonderful Tech Formulas....this is a good place to be!

 

[Screaming Metal]

I've seen some Drag cars in past decades, idling at 6 to 8 PSI with the SBC. During a pass, pressure hits 45 to 65 PSI....gotta have that cushion for the mains!, but more importantly, the rods.
Since that car sat up so long, I'd find a good mechanic friend to get some Riselone and flush it out. That long, starting and stopping, that oil can get to be sticky like Gearoil. If they started it everymonth religiously for that time, letting the motor get up to temp. every time, you'd be OK.
I'd still flush it to be on the safe side....Or at least change your oil twice within the next month. You'd be suprised how much goo comes out....they design oil to be pumped, getting hot and lubricating parts....they don't design oil to sit.
They do make a special oil....its real light weight, has alot of load additives, and you can even crank and run the motor some. But its made to be drained out before you leave the dealership. (Its used in very exotic HiDollar Sportscars) Its mostly a AntiRust,and AntiSeal Hardening agent....similiar to kerosene but thicker and has lubrication properties.

 

[Nat3dog]

Thank you all for the info and suggestions. I did an oil change on it and added some lucas oil treatment to it. It was running good but the longer it ran the lower the pressure went. I did some reading online last night and it sounds like chevy 305's are known for running with low pressure. A lot of what I read said to worry more about it if the oil gauge was not doing any thing and staying on low.It is running fine not getting too hot or making any odd sounds so think I am just going to drive it around my neighborhood and see how it does. I took it out last night and it ran great.

 

[WMG]

Thank you all for the info and suggestions. I did an oil change on it and added some lucas oil treatment to it. It was running good but the longer it ran the lower the pressure went. I did some reading online last night and it sounds like chevy 305's are known for running with low pressure. A lot of what I read said to worry more about it if the oil gauge was not doing any thing and staying on low.It is running fine not getting too hot or making any odd sounds so think I am just going to drive it around my neighborhood and see how it does. I took it out last night and it ran great.

I have a 305 in my T as well. At idle when the engine is warmed up the mechanical gauge reads right at or slightly below 20psi, as I drive and the RPM's go up the pressure tops out at around 45psi. Has been like this all the time I am running 5w-30 full synthetic oil and because of time span change it every 2500 miles no problems for years with it.

 

[Nat3dog]

5w-30 is what I put in it also. I wonder if having a battery that did not have enough amps might show a faulty reading?

 

[Screaming Metal]

Best thing to do is unscrew the sender unit, and screw in a good mechanical gauge to start, and see exactly what you got. If your uncomfortable with the low oil pressure, rest assured, your pressure is good if your idling at 20 and going down the highway its 45 to 55 psi.
As long as you don't have any wild fluctuations, pressure going up and down with the mechanical, you should be OK.
After you screw back in the sender, clean your connections to said sender and to back of gauge. Make sure the connections are tight. Then hook up and see what the electrics reading is compared to the mechanical.
All my motors, I wire up Hobbs switches, that way, if you loose pressure, you won't kill the motor. If your in a warmer climate, go with a slightly heavier oil, that will raise your pressure.
Theres really no reason to go with a 5w30 on a street car....for the bearings and general architecture, layout and function of our motors, 10w30 racing oil with all the good things in it is quite good. Plus your not gonna be driving it in cold weather. If your in Sunny Ca., you could almost run a single wt. racing oil, or in Hawaii or Arizona....

 

[railroad]

Ditto on the 10w-30. I was wondering why no one had asked or mentioned what oil you are using, unless I missed it. Any 10w 30 or 40 should be good. They do make some 15 and 20w's if want to try them. I do not want to start an oil wt debate, since you sound like you are in good hands.

 

[Mike]

I do not want to start an oil wt debate, since you sound like you are in good hands.

But if we point out that low weight oils can make more power, we'll have them all running to the shops in search of 5W oil.

 

[Screaming Metal]

Hahaha....got that Right, Mike!

 

[Wild Mango]

I've seen some Drag cars in past decades, idling at 6 to 8 PSI with the SBC. During a pass, pressure hits 45 to 65 PSI....gotta have that cushion for the mains!, but more importantly, the rods.
Since that car sat up so long, I'd find a good mechanic friend to get some Riselone and flush it out. That long, starting and stopping, that oil can get to be sticky like Gearoil. If they started it everymonth religiously for that time, letting the motor get up to temp. every time, you'd be OK.
I'd still flush it to be on the safe side....Or at least change your oil twice within the next month. You'd be suprised how much goo comes out....they design oil to be pumped, getting hot and lubricating parts....they don't design oil to sit.
They do make a special oil....its real light weight, has alot of load additives, and you can even crank and run the motor some. But its made to be drained out before you leave the dealership. (Its used in very exotic HiDollar Sportscars) Its mostly a AntiRust,and AntiSeal Hardening agent....similiar to kerosene but thicker and has lubrication properties.

Screamin' you can use Dexron as a preservative and flushing oil. As you say, can run the motor up to temperature (I wouldn't drive or fan it) and Dexron has good stuff in it for seals. Dexron is a very high film strength, and high detergent lubricant and it really flushes out the goop. Strangely, the stuff behaves like it has quite low viscosity but idle oil pressure is usually close to the same as normal lube oil. Used it all my life in the methanol open wheel engines to flush out that milky methanol contaminated lube that is so corrosive. Also use it 50/50 with pump gas to flush the fuel lines and coat the engine internals after a meeting. Good stuff, Dexron.

 

[Nat3dog]

Well I took the bucket out yesterday and drove the hell out of it just to see if any thing would happen. It ran great with out any problem from the motor. I did notice that if I drive over 50mph the drivers side front tire started wobbling some. I am not sure what would cause this but I do not go over 50mph most the time so not sure if this is some thing I have to worry about.

 

[Screaming Metal]

Well, the tire wobbling isn't good....need to fix that right away. Could be loose wheel bearing, loose or worn out KingPin, Tie-Rod end slop. or threaded shaft loose or any manner of evilness....
All the others will be here shortly.... is your steering box tight? Sector adjustment? Thought I might mention it since the bell-housing was loose. If no looseness, could be the start of the dreaded Death-wobble....

Look at your front tires closely, is there any wear on the edges of your tires? Grab that drivers side tire and try to shake it both side to side. is there a bumping sound? Also, try turning the wheel at the wheel like your spinning the steering wheel back and forth. Any bumping sounds or slack?

 

[EX JUNK]

You might want to check the balance of that tire. Usually at around 50 MPH is when an imbalance shows up but a lot of times it goes away above 65 MPH. Ai least that has been my experience in the past on different vehicles.

Jim

 

[392 Hemi T]

I had electrical gauges in my and they are way off as much as 25 pounds on the oil perssure .... Going to mechanical thinking thats the way to go