A lot easier on motor oil?
Are highway miles really....
- Thread starter trey
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Easier than stop and go driving. I would think that the absolute easiest driving in regards to motor oil would be maybe 30-35 MPH without stopping along a flat road. That would also provide optimal fuel economy.
Easier than stop and go driving. I would think that the absolute easiest driving in regards to motor oil would be maybe 30-35 MPH without stopping along a flat road. That would also provide optimal fuel economy. [/QB][/QUOTE]Good point. I notice if I run really hard on the freeway my oil pressure will drop some (assume the oil is running hotter) and then I get on the surface streets and it recovers. Freeway at 60 mph is probably very easy on the oil as is a nice 30-35 mph cruise along a parkway. Another thing that gets the oil hot is rpms. I can lower the oil pressure a bit just by locking out overdrive on the freeway in my motorhome and the oil will get hotter (more friction with faster moving piston at 3000 rpm vs 2400 rpm in OD). Freeway with a strong headwind will do it too.
Stop and go is tough as are short trips. Worst probably is shutting down when the oil has not reached opererating tempereature. How about folks who have to jocky cars in and out of the driveway every day to let someone else out. Loads the oil up with combustion byproducts.
Depending on the vehicle, optimal fuel economy usually comes somewhere between 50 and 65 mph. That's the ONLY reason we had the 55 mph speed limit back in the day.
Just driving along a flat road at 55 mph would be very, very easy on the oil!
I have about a 50/50 mix of city and highway driving, I run Mobil 1 5w30 10,000 miles between changes. If i drove 90% highway miles I would go to 20,000 mile changes.
With my current oil I ran 4,000 miles to the west coast, oil was not even discolored, no useage (normally uses 1 pint ib 5,000 miles), have 6,500 miles on it now and still looks very clean, still no usage.
With my current oil I ran 4,000 miles to the west coast, oil was not even discolored, no useage (normally uses 1 pint ib 5,000 miles), have 6,500 miles on it now and still looks very clean, still no usage.
Perhaps one should schedule oil changes according to total fuel consumed, which would automoatically result in a shorter OCI for city driving, copious idling or cold starts, etc.
Cruising at a steady 65mph / 105kph is extremely easy on today's engines, which are typically turning about 2500RPM under a light load. With most cars, cruising on the freeway requires less than 15hp of engine output power.
Cruising at a steady 65mph / 105kph is extremely easy on today's engines, which are typically turning about 2500RPM under a light load. With most cars, cruising on the freeway requires less than 15hp of engine output power.
Kestas
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Yes... I've seen data where they measured the wear in the engine uder different driving conditions - highway, stop & go, idling. They somehow made the parts radioactive and measured the radioactivity of the oil as it got contaminated with engine wear debris.
I guess in a purist kind of way this measured engine wear instead of oil wear, but don't the two usually go hand-in-hand?
I guess in a purist kind of way this measured engine wear instead of oil wear, but don't the two usually go hand-in-hand?
I know it's easy on the oil, but I've heard from some sources that freeway speeds aren't necessarily optimal for fuel economy because wind and rolling resistance are higher. The 55 MPH speed limit was supposed to be a compromise. We're probably splitting hairs though, since the most important thing for achieving high fuel economy is not stopping and releasing energy into the brakes.
Some of the new hybrids are actually rated higher in city driving, where the regenerative braking systems recapture the energy that would normally have been converted to braking heat.
Yes, that's true, I was talking more on the lines of the 1 hr commute some people have driving 15 miles in bumper to bumper traffic, where the oil temp gets up to temp, as opposed to my 1 hr commute @ 60mph the whole way. Short trip vehicles are a totaly different thing than either one of these IMO.
Not sure which is worse, the short trips or the long idle/ stop and go of loft traffic.
Most often, yes. However, the only reason that is so is because on the hwy/fwy the oil is fully warmed and working. Short trips and stop/go the oil temp will go down and condensation and fuel will not burn off. That's the ONLY way/reason it's harder on the oil.
thanks for the replys guys, i was just asking cause recently i moved and now currently am driving about 95% highway.
just so you know why hyw is easier on oil.
as your going 55-70 mhp, you have full hydrodynamic lubrication, so in a since, you have oil all around your bearings. where as, when your doing stop and go, you only get partial amount of oil on your bearings so when you start to stop, you tend to squeeze out the oil between your bearing and the piston and cause more wear. that is why you see proffesional racers race up the motors before taking off the race line. They are building up the lubrication between the bearing and the piston before dumping the clutch.
so hwy is much easier on oil verses stop and go. It doesn't shear the oil on the hwy, where it does in town stop and go. the effects of oil shearing . this site will explain what I'm saying.
as your going 55-70 mhp, you have full hydrodynamic lubrication, so in a since, you have oil all around your bearings. where as, when your doing stop and go, you only get partial amount of oil on your bearings so when you start to stop, you tend to squeeze out the oil between your bearing and the piston and cause more wear. that is why you see proffesional racers race up the motors before taking off the race line. They are building up the lubrication between the bearing and the piston before dumping the clutch.
so hwy is much easier on oil verses stop and go. It doesn't shear the oil on the hwy, where it does in town stop and go. the effects of oil shearing . this site will explain what I'm saying.
I think John_E has hit on a good idea. Get a Hobbs meter that reads gallons of gasoline consumed instead of engine hours. Set your oci on gallons of gas used. We can call it the 'John E Meter' and when you've used up enough gasoline you can take your car to the John for an oil change. Working hard and working long are not always the same thing and the John E Meter could be the answer. The John E Meter might be even better than the GM oil change monitor, especially if you believe in Acham's razor.
I would think that with stop and go traffic, oil would get heated up more than constant highway driving. Greater heat = less oil life.
Bob, good to see you!
Bob, good to see you!
Probably not for short trips though. Some people with oil temp gauges have noted that short trip stop & go doesn't get the oil up to full coolant temps, but a longish highway drive will. The hardest thing about short trips will be condensation, while the stop & go will shear the oil.
Are you sure about that? I've always heard that they do that so they don't stall the car, due to the "hair-trigger" race clutches they use which are tricky/impossible to modulate like the clutch on a street-driven car.
If the idea is that if you're getting city fuel mileage, you should use a severe service interval, and if you're getting highway fuel mileage, you should use a normal service interval..
This is what I figured out for my car, which has a severe interval of 3000 miles, a normal interval of 5000 miles, and 21/31 city/highway mileage:
5000 minus 3000 equals 2000 miles
31 EPA highway minus 21 EPA city equals 10
2000 / 10 = 200
Then subtract EPA city rating (21MPG) from the actual mileage: I get 28MPG so I end up with 7.
Multiply 7 times 200, come up with 1400, add that to 3000 and 4400 miles is the interval.
If I were getting 31MPG, I'd multiply 10 times 200, come up with 2000, add that to 3000 and 5000 miles is the interval.
If I were getting 22MPG, I'd multiply 1 times 200, come up with 200, add that to 3000 and 3200 miles is the interval.
I dont think the racers are thinking about lubrication when they rev the motor to take off...in drag racing the objective is to "shock" the tires...they want a sudden application of power, not a slow gradual buildup...the car is going to move when they "dump the clutch" in either scenario, but that engine making a ton more HP at high rpm than near idle. Most Pro Stock drag cars, at least used to be when i was involved, have a basically two rev limiters...one for burn outs, to heat the tires, and another, set at a higher rpm, for the actual launch...so in effect, for consistency, they just floor it...the rev limiter holding the engine at whatever rpm they want to launch at...
In road racing, and the reality show called NASCAR, they rev that motor for faster getaway AND to ensure it dont stall....if it stalls it may or maynot restart, dramatically changing track position...
Just IMHO, YMMV
darrell
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