oil pressure??? 6.0 litre

[Wtfman]

In the morning when i fire up my truck the oil pressure is erratic. Upon a cold start the oil

pressure climbs to 40 lbs, but then it goes down to almost 20lbs and then back up to 40lbs.(this

fluctuation of oil pressure continuies until its hot). When its cold it will never get more than 40lbs

even if I spike it. After the motor is up to normal operating temp i get as much as 65lbs and the oil

pressure willl go up with rpm increase from 40lbs to around 60lbs. Any suggestions would be awesome

thanks.

[mwid73]

It's possible you may have a bad sending unit to the guage. Generally, you should have higher pressure upon cold start up as the oil thins down when hot causing pressure to drop a slight bit. My '02 1500HD is about 65lbs. at initial start up then drops to about 45lbs. when good and warm. At 65 - 75 mph on the road it'll run right at 55lbs.

What year is the truck?? How many miles??

[Wtfman]

Hmmm... Maybe. The truck is a 2000 chevy silverado 149k other than that the motor is still strong. I am familiar with cold starts and the oil pressure being higher as the oil viscosity is higher, thus making the oil pressure higher. This is what it used to do until a month ago it started acting weird I would assume its the sending unit as the truck isnt making noise when the oil pressure is fluctuating some 20 pounds. I mean it jus doesnt seem right to have a good running motor fluctuate oil pressure that drammatically, and when she is hot have optimum oil pressure. Unless its worn out and the heat makes the clearences tighter to increase oil pressure, but I doubt this.
Thanks for the advice man.

[j cAT]

Originally Posted by Wtfman

In the morning when i fire up my truck the oil pressure is erratic. Upon a cold start the oil

pressure climbs to 40 lbs, but then it goes down to almost 20lbs and then back up to 40lbs.(this

fluctuation of oil pressure continuies until its hot). When its cold it will never get more than 40lbs

even if I spike it. After the motor is up to normal operating temp i get as much as 65lbs and the oil

pressure willl go up with rpm increase from 40lbs to around 60lbs. Any suggestions would be awesome

thanks.

with my 2000 5.3L with dino oil on cold start below 30 deg F , the oil pressure will be 75psi...then as the oil warms drops back down to 40- 55 psi...

with the synthetic mobil 1 5-30wt same cold start the pressure climbs to 65 psi at normal temp 45-65psi...

as you can see the synthetic flows better than dino oil when cold as no high pressures ...also when the engine is at temp the synthetic oil gives me 5psi or so higher pressures..


since the pressures are low on cold start I would need oil type viscosity/ filter used / condition of oil/change interval..

it may indicate a lot of sludge in the oil pan restricting the flow thru the sump screen...when cold this is very goopy..this also may indicate changing the oil when cold ..cold oil changes are a good way to damage the engine..as this debis never gets removed..

[Wtfman]

The oil i run is 15 40 delo 400 with a K&N oil filter. I know this oil is too thick, however the motor makes a clicking noise at idle when i run mobil 1 5w 30. This noise has been consistent since brand new and it runs great otherwise. What should i do to cure my issue as I do not want to hurt the motor?

[j cAT]

Originally Posted by Wtfman

The oil i run is 15 40 delo 400 with a K&N oil filter. I know this oil is too thick, however the motor makes a clicking noise at idle when i run mobil 1 5w 30. This noise has been consistent since brand new and it runs great otherwise. What should i do to cure my issue as I do not want to hurt the motor?

I like the oil filter but the 15-40 wt is a no no.....this explains why this is screwed up/.....5-30wt is the correct oil...if you have lifter noise use the marvel mystery oil at 1 ounce /qt of engine oil ...6 ounces max in the crankcase...this will remove the carbon and other contaminates that are causing the lifters to not properly hold oil...also this should clean up the oil pan and oil pump sump screen,,,,always change oil when hot ...

what KN filter do you use ?

[Wtfman]

Okay cool ill change it tomorrow and put the specified oil in it, along with marvel mystery and see if it helps. The K&n oil filter is jus one you can pick up at kragen. I use the one it calls for forgot the part number but ill get it for you...
Thanks J cat! hopefully that oil hasnt messed anything up

[j cAT]

Originally Posted by Wtfman

Okay cool ill change it tomorrow and put the specified oil in it, along with marvel mystery and see if it helps. The K&n oil filter is jus one you can pick up at kragen. I use the one it calls for forgot the part number but ill get it for you...
Thanks J cat! hopefully that oil hasnt messed anything up

my engine had those issues when new...the engine now still runs better than new ...no oil consumption or noises...I had a lot of lifter noise when less the 10,ooomi...the marvel cleanout whatever GM did not properly clean the engine oil passage ways..

post back after a week of operation with how it worked out..good luck ..

[Wtfman]

J cat, so I changed the oil to kendall 30w and added a WIX filter. A friend of mine was there that is a technician and told me that it wouldn't be a bad idea to add the entire pint of marvel mystery to the oil so i did...He did say to change it at about 1500 miles also. Since i have put about 25 miles on the truck it seems to be helping my pressure issue. Will this hurt the motor as the back of the bottle states to put the whole thing in??? i was a little worried about that much because you said only 6 ounces max, but the tech said it would be fine???

[j cAT]

Originally Posted by Wtfman

J cat, so I changed the oil to kendall 30w and added a WIX filter. A friend of mine was there that is a technician and told me that it wouldn't be a bad idea to add the entire pint of marvel mystery to the oil so i did...He did say to change it at about 1500 miles also. Since i have put about 25 miles on the truck it seems to be helping my pressure issue. Will this hurt the motor as the back of the bottle states to put the whole thing in??? i was a little worried about that much because you said only 6 ounces max, but the tech said it would be fine???

as you mentioned I stated 6 ounces max...you put in 16 ounces ...the reason I said 6 is because this is a safe amount...also you installed 30wt oil as you know this engine must use 5-30wt oil...this is the designed wt to use ...10-30wt is ok also..

you must closely monitor the oil color when it gets very dark change the oil and filter and then add the correct oil and amount of marvel....

the reason to add only the amout I stated is you do not want to lossen up toooo much goop at once...this can cause problems....

also adding too much marvel thins the oil too much this then is not good....

what pressures do you have now ...also on cold start how is the pressure and did the lifter noise quiet down ?

[Wtfman]

Hey man, so I understand what you are saying as it makes perfect sense...
First cold start w/marvel mystery oil:
The oil pressure seems to be getting better along with the clicking noise. Today was about 40 degrees and upon cold start the oil pressure built up slowly and stopped at about 40psi...
As the motor began to heat up the pressure seems to stabilize faster than before and never dropped below 35 psi...
The clicking noise was present on initial fire up but subsided to zero noise once hot.
After the truck was good and hot I then prooceeded to rev a bit taking it to about 3.5 rpm the oil pressure climbs to 65 pounds without problem.
I then shut the motor down and checked the oil which was clean like brand new.

Also I recently installed electric fans which gave me a bunch of power

Initial cold start up 35 to 40 psi

[j cAT]

Originally Posted by Wtfman

Hey man, so I understand what you are saying as it makes perfect sense...
First cold start w/marvel mystery oil:
The oil pressure seems to be getting better along with the clicking noise. Today was about 40 degrees and upon cold start the oil pressure built up slowly and stopped at about 40psi...
As the motor began to heat up the pressure seems to stabilize faster than before and never dropped below 35 psi...
The clicking noise was present on initial fire up but subsided to zero noise once hot.
After the truck was good and hot I then prooceeded to rev a bit taking it to about 3.5 rpm the oil pressure climbs to 65 pounds without problem.
I then shut the motor down and checked the oil which was clean like brand new.

Also I recently installed electric fans which gave me a bunch of power

Initial cold start up 35 to 40 psi

this is good as you only have a sludge carbon build up...after about 500mi you should not have any noises , or at the worst 5 sec of noise on a cold over night start...

just keep an eye on the oil it takes some time for the carbon to be removed..carbon is what eats at the internal engine componets ...your filter is very high rated and should trap most ....when it can no longer filter correctly the oil will darken this is the time to change the oil , doing this hot is most important...

post back after several hundred miles of operation with any comments

good luck..

[Wtfman]

hey so I did the marvel mystery oil, and still upon cold starts I dont get optimum oil pressure. However it has gotten better, as now I get around 40 pounds of pressure and it does not fluctuate as much.

Would it be a good Idea to drop the oil pan and clean the pick up???

By the way i now have to do the heater core, as the heater does not get hot(it only gets warm) big fun.

[j cAT]

Originally Posted by Wtfman

hey so I did the marvel mystery oil, and still upon cold starts I dont get optimum oil pressure. However it has gotten better, as now I get around 40 pounds of pressure and it does not fluctuate as much.

Would it be a good Idea to drop the oil pan and clean the pick up???

By the way i now have to do the heater core, as the heater does not get hot(it only gets warm) big fun.

with the use of the 30wt oil this will cause the pressure to rise slowly on cold start..if the air temp where 90deg f maybe not..

whenever replacing the coolant you must remove the heatercore hoses at the engine and using a water hose continue to reverse hoses until the water flows fully..this is a common problem as few do this when the coolant is replaced...also there is no coolant valve....it flows all the time ...

if you for some reason cannot get a good flow replacement is the dash removal ...so that is a very big job..

[Wtfman]

At the moment the air temp is cold so ill see how it acts in the summer... I did run the hose through both ways until good flow was produced and the heater now rips out the heat so good call on that bro...
I really appreciate all the advice big man, thanks...