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Oil change, 5w30 to 10w30?

With 235k miles, I am 4,000 miles into this oil change, I am soon to change my oil in the next week. Has anyone else used 10w30 instead of 5w30 because of the wear of engine so it has more oil pressure?

I don’t know if Rolls Royce allows this.
Oh? You don’t have a Rolls? Well than, what year make and model of car are we talking about?

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1994 silverado. Same 350 5.7 mostly all older silverados have

Why bother, if it has gone this far on 5w30 ? If it makes you feel better you could use oil labeled as ‘high mileage’

I doubt that going from 5W-30 to 10W-30 will make any discernable difference in the oil pressure. The 10W-30 won’t flow as freely when the engine is cold and a lot of the engine wear occurs on startup. The dealer put 10W-30 in the 4Runner we own that calls for 5W-30 and it didn’t make any difference. A independent shop put 5W-20 in an Uplander we owned instead of the correct.5W-30 and it didn’t make any difference. I made certain the specified oil was put in at the subsequent oil change.

I’m inclined to agree. Why change what’s worked so well?
Your owner’s manual may even offer 10W oil as an option, giving you the freedom to switch with confidence if you desire.


My owner’s manual lists acceptable alternate oil weights depending on temperatures where the vehicle is normally operated.

5-30 flows the same as 10-30 when both are hot. the 2nd number is the normal operating temp viscosity. if the spec is 10-30 and you are worried about worn bearings than use 10-40. or use 4qts of 10-30 and 1 qt of 10-40


@cavell gave good advice concerning oil flow when the engine is warmed up. The other issue is start-up. When the engine starts, the 5W30 will lubricate better than the 10W30 will. Since most wear occurs at start-up, using 10W30 (or 10W40) will increase engine wear compared to 5W30. Do you have excessive engine wear or is this just to prevent wear in the future? If you don’t have an oil pressure problem now, just keep using the 5W30.


So here’s an additional question: is 5W40 worth considering by the OP to try something without changing start-up conditions?

I’d avoid that. Viscosity modifiers are microscopic polymer coils that unwind with heat and enlarge, enhancing the oil’s ability to resist flow. However the polymer coils don’t lubricate as well as the oil. Oil experts recommend that you not go too high between the base number and the modified number. Mixing too much viscosity modifier into the oil has an adverse effect on the lubrication.

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What’s your weather like @Devon_Allision? If you live in Brownsville switching to 10W30 might be of some benefit but if that engine is running well and not using excessive oil with all those miles I’d say stick with the one that brought you as others have recommended.

Interesting. So for whom do they make the 5W40?

And there’s the 0W40 “European blend” Mobil 1, which seems common (like 5W40, which doesn’t seem rare)

Anyone willing to purchase it.
Lots of stuff is on the market that I wouldn’t advise. Like toilet-paper oil filters. And tires with a 30 aspect ratio. And lowering springs for Civics. Oh, and those ten-million watt audio systems with four 16" woofers that make the ground shake.

I will be warmed up and at a stop light and I will have almost 0 oil pressure

dash gauge? you could try a mechanical gauge but with 235k miles i would vote for worn bearings. you get to a point where the motor needs overhauling. or replacing. 24yr old truck is getting up there. what state are you in?

Unless it is actually knocking, which requires immediate attention. The first thing to do is have the oil pressure mechanically checked. It could just be a sending unit or gauge problem.

Have you checked this with a separate gage? Gages on the dash can have enough error to cause false conclusions.

If with a test gage T-ed in you still get near-zero pressure, that’s a sign of wear. Oil pressure is created by the pump forcing the oil through the wee spaces between the bearings and their corresponding surfaces. That’s what creates the pressurized fluid barrier that protects the engine from wear. When these spaces wear too large, there’s no longer sufficient resistance to the pump’s forces to support pressure. The oil simply flows through easily.

BUT: test, don’t assume. Post the results.

Its already been rebuilt once, but it doesn’t have any mechanical problems, just worn bearings that I have noticed

Have the bearings been knocking? If so, that supports the wear theory. Rod bearings in particular will knock, because they get banged sideways by the combustion with every shot of the sparkplug.

If that’s the case, I support trying a heavier base weight oil. You’ve nothing to lose and just might stretch the engine’s usable life a bit. It’s a longshot, but sometimes those work.