Hypothetical example: The manual says 5W20 or 5W30 should be used. After 150K miles, does a person need to jump up to 5W40 to get the same effect that the previous oil provided when the car was newer?
Choice of oil and maintenance shouldn't be based solely on mileage, but mostly based on symptoms. i.e. - appropriate medicine for the symptoms/condition of the specific patient. A doctor doesn't automatically put an old man on heart medication just because he turned 65 or 70. A doctor bases treatment mostly on the patient's symptoms and condition and only somewhat on patient's age.
If an engine (of any mileage) is not burning or leaking oil, then there's
no need for high mileage oil, no need for Valvoline Restore and Protect, and no need to go to a thicker grade of oil.
If engine is burning or leaking oil, then do the things listed below.
1) If engine starts burning or leaking oil, remove the PCV. If it doesn't rattle when you gently shake it, then clean it with brake cleaner or throttle body/carb cleaner until it rattles easily. If the PCV still won't rattle, replace it.
If you're too lazy (or too efficient) to clean a PCV, or just don't have time for that, then skip trying to clean the old PCV and buy a new one. A new PCV is not expensive. A new GM ACDelco/Buick PCV only cost me $7.50 from local autostore. A new autostore housebrand PCV for a Honda CRV only cost me $14 and works fine. An OEM Honda PCV would have cost me $30. A new PCV is cheap maintenance that can signifigantly reduce oil buring and/or leaking.
2) If PCV is attached to a rubber breather hose (as it is on some cars), check the hose for shrinkage, kinks, obstructions. Clean or replace hose if needed.
I completely cured/stopped severe oil burning in a Honda CRV just by replacing the shriveled, kinked breather hose that attached to the PCV. Other cars (like my Buick) have no breather hose.
3) The above maintenance is sometimes enough to cure or reduce oil burning and/or leaking, but if it still burns or leaks, then switch to a high mileage oil in the original/recommended viscosity. Try that for 5000 miles.
4) Then, if it still burns or leaks oil, go up one grade thicker in high mileage oil.
Note: Some brands of high mileage oil are thicker than others (even in same stated viscosity grade). I prefer and recommend the brands of High Mileage oil that are thicker than most because thicker tends to be more effective at reducing burning and leaking. (Which brands of High Mileage oil that I recommend is a topic for another post.)
Those ^ are classic, traditional fixes for oil burning and/or leaking.
In recent times, there's also another solution you can try for oil burning engines. You can try using Valvoline Restore and Protect (Valvoline Restore and Protect) oil for 4 oil change intervals to clean piston rings to (hopefully) reduce oil burning. This
sometimes reduces oil burning by cleaning/freeing stuck oil ring in pistons.
Valvoline Restore and Protect is
sometimes a solution for oil burning, but not for leaks. High Mileage oil can reduce burning and leaking, though
sometimes it's not enough. Sometimes new rings or new seals/gaskets are needed.
Choice of oil can usually reduce, or possibly eliminate,
minor high mileage related problems. Choice of oil cannot fix major problems. Only hands-on maintenance or repair can fix major problems. Even some minor problems (dirty/stuck PCV for example) need hands on maintenance.
If you try Valvoline Restore and Protect for 4 oil change intervals, then switch to a high mileage oil.
