Wrong oil, will it damage the engine?

chevrolet
suburban

#1

I changed the oil in my suburban last week and after I changed it I noticed on the oil cap,stamped into the plastic, it said 5W30,but i used 10w30 and a quart of Duralube.ever since i changed it Ive noticed that for about the first 5 minutes after starting the engine when its cold, the oil pressure stays at 60 PSI and then over the next 1-2 minutes slowly drops down to 40 psi,which is the normal pressure.
is 60 PSI too high? will it damage the oil pump or the oil seals?


#2

NO. If this is the Suburban you bought used with the bad brake lines I can almost guarantee it has had all kinds of oil in it over the years.


#3

No, it will not hurt the pump or the seals. Oil pressure is created by the pump trying to push oil through all the very small spaces (between the sleeve bearings and their corresponding surfaces) and orifices that it needs to for the oil to provide the pressurized fluid barriers that protect the parts. The pressure is initially higher because until the oil warms and thins out a bit, it’s harder to push through the spaces. Slightly thinker oil should be fine… but I’ve said this not knowing the year, engine, or mileage on the engine. That information really would be nice to have. I could tell from that things like (1) does the engine have wear on it or is it still tight, and (2) is the oil being used to also operate the variable valve timing system (This feature uses oil like a hydraulic fluid, and old engines didn’t have this modern feature). For the record, we should not be expected to go searching for your other posts to find this out. This information should be in the post. Sooooooo???


#4

yep, its the same one, i replaced all the rusted brake lines, both of the front calipers, both of the rear wheel cylinders, the rear brake shoes, the front brake pads,and the master cylinder.The brake pedal feels real good now it stops on a dime, and surprisingly I didnt have any problem bleeding the brakes even with the ABS.
after doing all that I thought i was done with brakes for a while but 2 days later my daughter calls and says dad the brakes on my nissan aren`t working right.I went and got her car and sure as shit a brake line under the driver side passenger door had rusted and ruptured.at that point i was glad that i had bought 100 feet of brake line, a tube bender and a flaring kit to do the suburban.


#5

its a 1999 suburban 5.7 liter V8 vortech engine, it has about 180,000 miles on it, it has a tow package on it with upgraded suspension,upgraded transmission and a transmission cooler, is that why it uses 5W30 instead of 10W30? ive never owned a vehicle that called for 5W30, they all used 10W30.i guess it makes sense that it would use heavier,thicker, weight oil for towing stuff so that the oil doesn`t break down too fast.


#6

No harm done, but Duralube is snake oil.


#7

That`s what my wife says, but I still remember watching an infomercial on late night T.V. like 30 years ago, where they put duralube in an engine and ran it for 15 minutes then they drained all the oil out and ran the engine for like 3 hours and it was still running without any oil in it 3 hours later.


#8

Nope. It uses lighter base weight oil because the spaces the oil needs to get between are tighter. But after 17 years of wear they’re likely larger than they were when the engine was new due to normal wear.

It’ll be perfectly fine with 10W30. You have enough wear on it that 10W30 might even be preferable… although please don’t take that as a recommendation. I don’t know enough about the engine’s internal condition to be making such a recommendation. It’s just an explanation of why I feel it’ll be fine.


#9

And you believed that infomercial?

I would change the oil before real cold weather.


#10

If the suburban is like my trailblazer the oil pressure gauge is just an estimated oil pressure not actual oil pressure. Always wondered why after 170k mY oil pressure has not changed a bit, 40psi at idle.Thought it was my good maintenance, but actually reflects nothing realistic.

Be careful about assuming that your oil pressure gauge is showing you any information about the health of your engine. All that it really tells you is that your oil pressure is something above a specified level (a value I couldn’t find in the manual but the minimum acceptable oil pressure is specified as 12 psi so it is probably a value below 12 psi)


#11

GM has specified 5W-30 (and warned specifically against 10w-40) starting around 30 years ago for all its light truck motors. I think some newer motors are supposed to use other weights.

I would change the oil using 5w-30 sooner rather than later.


#12

so i should use thicker heavier oil in the winter?
I thought you were suppose to use thinner oil in cold weather and thicker oil in hot weather?

I remember when i had a suzuki 750 motorcycle and in the summer,no matter how thick and heavy oil i used, in the summer i could see the oil boiling and bubbling through the sight glass on the side of the engine.I kept putting thicker oil in it and within days the oil was the consistancey of water.


#13

I have no problem with doing that, its an old truck so it may not be very tolerant of the wrong oil thats why i asked on here.ill get some 5w30 tomorrow and change it,oil is cheap, a new engine isnt so cheap.


#14

If a manufacturer recommends different viscosities of oil, a temperature chart will be included in the owners manual, with thinner oils being recommended for lower temperatures.

GM recommends 5w-30 for your vehicle year-round.


#15

Thinner in winter, 5w-30 is thinner when the engine is cold.


#16

oh ok, the lower number equals thinner,so that would explain why the pressure is higher because the oil pump is trying to pump thicker oil through the engine. i`ll definately change the oil tomorrow.an oil change is cheaper than replacing an oil pump that wore out prematurely from pumping oil that is too thick


#17

I’m down to 0-20 myself so I guess I’d go with what’s recommended sooner than later. I saw an infomercial where the guy went out in the everglades with alligators and snakes with an air boat made of screen but painted with the miracle water proofing paint. Yeah sure. I believe everything on TV. Thing is, who was filming the whole thing? Must have been there to pick the guy up when the boat started sinking. Slick 50, Duralube, yeah probably do more harm than the thicker oil.


#18

Re- that Duralube commercial where they run the engine 30 minutes without oil.

My son purchased a 1974 Plymouth duster with a slant six at a notorious used car cot, while I was away on vacation. It had no pep, sometimes overheated and got lousy gas mileage.

After a YEAR of this, the engine seized, not near his house,but near mine. We towed it to my house and my son in law and I changed the engine ( $50
at a local junkyard, those engines were plentiful and cheap)

Before my son drove off with the car, I rolled the bad engine over and pulled the oil pan and found no gear on the distributor shaft to drive the oil pump, the pieces of the gear were in the sludge in the bottom of the pan.

I asked my son how long the oil pressure light had been on. He said it had never come on so I went in the car and turned the key. Sure enough, no light. I reached up behind the dash and polled that socket and found no bulb. That car had no oil pump when he bought it.

I should mention that the inside of the engine was coated with what looked like dry fluffy soot.


#19

GM spec’d 5-30W for a reason I expect. Unless the owner’s manual gives you some leeway, stick to the same oil specs what the GM engineers think the engine needs. I doubt however you’d run into any substantial difficulty using 10-30W as other here have noted, unless your vehicle’s engine has a variable valve timing design, which is very much not tolerant of the wrong oil specs.


#20

I use Lucas oil stabilizer religiously with every oil change on a 1997 Acura CL. I don’t know what it does to the engine, but it makes a significant difference. The engine runs extremely quit and smooth with that stuff added. Without it is much more noisy and starts in the morning with a loud “ticking” noise.