Straight weight oils are for air cooled engines these days, multi grade oils get too hot and turn the tricky bit that makes them change viscosity as the oil heats up into nitride (I think that's what they're called) particles that score the bore and cause excess oil consumption in an engine that was otherwise operating well. The scores in the bore lead to ring blow by and oil ends up leaking out of everywhere, even through the alloy cases in British built engines.BernieQ2 wrote: ↑Tue Oct 03, 2023 6:36 am Good morning.
Another relaxing day...over the back had tree cutters in so that was a bit of excitement
Not much else going on in town...Carol had a small win at bingo...plus all the gossip
Except for opening the door I done little in the motorhome, me thinks herself is going to clean in side of it today
Terry if you are about ...can I run straight 30 grade oil in the Hino engine, other than multigrade
Keep safe everyone.
Bernie.
As Bruce says, it is the upper number that is critical .... to an extent .... at the upper temp range, the oil will still be the viscosity of 5w oil, where straight 30w would be like tar when very cold and petrol when at the max operating temp range.
If you see the oil pressure is high when the engine is cold, the first number needs to be lower, the oil is too thick and is not getting to the places it needs to reach when the engine first starts up.
If the oil pressure is low when the engine is hot and idling, like low enough to make the light blink, the upper number needs to be higher because the oil is thinning out to the point it is running past the worn bits like bearing shells and the pump can't keep up ..... replacing the bearing shells and fixing the oil pump or upgrading it to a higher flow pump will fix the low oil pressure when hot and reduce the oil consumption because the cyl bores are not being flooded with the oil being pumped out of the bearing to crank gap as the piston changes from being held down going up on the exhaust stroke to the being pulled back down on the intake stroke ..... that is the bearing rattle the trained ear can recognise, not on the compression and expansion stroke, the piston is always in the loaded and held down state during that part of the cycle .......
No matter how thick the oil is, if the bore is scored or the oil control rings worn or clogged and the second ring worn rounded rather than shape on the edges to act as an oil scrapper, oil will still pump onto the top of the piston .... if the valve guides are worn and/or the valve stem seals are damaged, there will be a big cloud of thick white smoke when the engine first fires up, hot or cold .....
Also, keep in mind, if the valve guides are worn excessively, when the head is removed, look for carbon build up around the outside edges of the piston, if it is clean around the bit closest to the bore, you need to do rings and bearings as well ..... every chance the diesel engine will not fire up once the oil running past the valve guides is fixed ..... that oil was sealing the rings to create compression for that first bang to get the whole combustion cycle happening ....
Thus ends the lesson on oil and engine wear diagnosis .....
T1 Terry
Good onya Shirley. No matter what the results, we will always support you. 
SFA...
