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| Thread ID: 135485 | 2013-11-09 06:04:00 | What grade engine oil? | pctek (84) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 1359284 | 2013-11-11 04:46:00 | Why does a 4 stroke lawnmower have recommended oil changes after 10 hours of running, when a vehicles 4 stroke engine can go 6 months or more of running on the same oil? air filter is part of it. oils fail due to contamination. they rarely "wear out". biggest source of the contamination is the poor combustion. crude fuel control, crude ignition, over fueling to cool the engine causes fuel wash into the oil. piston ring design and being splashed lube will have a bit to do with it to, ie the amount of blowby past the rings. a mono oil like sae30 is a better oil than most multi grades. |
tweak'e (69) | ||
| 1359285 | 2013-11-11 05:49:00 | Multigrade oil is usually specified for motor vehicles which often run cold and start/stop a lot. They also emulsify with water so that should you have an internal water leak the oil will have a milky appearance. It will also prevent the oil pump from drawing pure water from the bottom of the sump causing engine seizure and rust. Single grade oil, usually SAE30, sometimes SAE50 is more suitable for air cooled motors which warm up quickly and run on the hot side. Regular short period oil changes are recommended because the sump capacity is only 1 pint, runs at high temperatures, in very dusty conditions, often with incorrect fuel mixture settings, and no oil filter. |
mzee (3324) | ||
| 1359286 | 2013-11-11 07:32:00 | :2cents: The older multigrade mineral oils which have long chain curly molecules (using viscosity index polymethyl methacrylate improver) do tend to wear out mechanically, the molecules get chopped up especially in gearboxes, and the oil tends to lose its multigrade characteristics as the molecules can no longer uncurl and get longer. | Terry Porritt (14) | ||
| 1359287 | 2013-11-11 09:51:00 | its still much the same today. they are thin oils thickened with viscosity improver's. rule of thumb is wider the viscosity rating the shorter its lifespan. mono oils are still in common use. |
tweak'e (69) | ||
| 1359288 | 2013-11-12 06:24:00 | I'll risk a small thread hijack with my own question... Why does a 4 stroke lawnmower have recommended oil changes after 10 hours of running, when a vehicles 4 stroke engine can go 6 months or more of running on the same oil? I would think it is because a lawnmower operates at its peak power, usually higher revs, so it cuts your grass good. In comparison a car engine spends most of it's life at low revs well below peak power, except mine, I like to utilize my power!, therefore less heat being transferred between components = less damage being done to the oil. As far as oil grade, I change mine summer to winter, I typically do a lot of short distance driving and the warm up time from winter to summer obviously changes so lighter oil in winter is in theory better for the engine. FYI running a car on fully synthetic oil hurts the wallet. |
hueybot3000 (3646) | ||
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