While reading another thread, I noticed a link to "Motor Oil University" on BITOG. Fascinating. Got me to rethinking my oil choice.
I've been driving Swedish turbo cars since 1983. Due to Tx heat, I've gone with thicker synthetic oils like 20W-50 or 15W-40 (with extended drain intervals of 10k mi. with an oil filter change at 5k mi.) But Haas has me rethinking this.
Don't experience deep cold here. Maybe a handfull of nights it'll hit 26F. The summers are brutal though: 105F in the shade, 120F in the sun, black asphalt at 140F. Can't remember what the thermostat is. But the coolant temp never varies from the 3 o'clock position, regardless of how hot (or how cold) it is outside.
The current sled, the Volvo, is the 2.3L, HP model. I don't put my foot in her much. Nor drive over 80mph on the freeway. Always let her warm up a bit before moving into "D". Currently at +182k mi, she doesn't burn a drop of oil.
There's too much info in his article to paste here and comment, but his points are well made. Thinner oil results in more flow which equals more cooling at a lower oil pressure.
Quote:
Increasing the pressure while using the same oil will increase the oil flow but increasing the pressure by increasing the oil thickness will result in less flow. It takes more pressure to move a thicker oil. When you go to a thicker oil the pressure goes up because of the increased resistance, and therefore reduction of flow. Because the pressure is higher sooner, the relief valve cuts in sooner. Flow will actually be less when the RPM is up and the flow is needed the most.
Didn't know this:
Quote:
The synthetic 10W-30 grade oil is based on a heavier 30 grade oil while the mineral based 10W-30 oil is based on a thinner 10 grade oil. They are both similar at operating temperatures yet the 30 grade based synthetic is actually less thick at startup and much less honey – like at low temperatures. This is the opposite of what common sense dictates.
Quote:
I truly believe that oil is much better being too thin than too thick. Over the years we have been going to thinner and thinner oils despite hotter engines with turbos and the like. The tendency is that people figure they need a 40 grade oils but then use a 50 instead. Better thinking is that if you think you need a 40, use a 30 grade oil instead. I firmly believe this based on all I know about oils.
Quote:
As it turns out synthetic oils do cling to parts better as they have higher film strength than mineral oils. Synthetics are thinner overall. They have greater slipperiness. Yet they stick better to engine parts. Again, this concept is the opposite of normal thinking.
The thickness of moving oil is measured in centiStokes or cS. Most engines want the oil viscosity to be around 10 cS at normal operating temperature. The really thick multi-grade oils have a viscosity of 20 cS at operating temperature. One is not twice as thick as the other, it is only 10 cS thicker.
As we increase the heat from 212°F to 302°F the most commonly recommended oil thins from 10 cS to 3 cS. The thicker oil drops from 20 cS to 4 cS. Note that in a very hot engine the difference between the two oils is now only 1 – 2 cS. In other words they have about the same thickness. There is little advantage to a thicker based oil as a 20W-50 at very high temperatures. No, the 4 cS oil is not twice as thick as the 2 or 3 cS oil. This difference is almost insignificant.
There is a huge advantage of using the thinner, 10W-30 at startup where 90 percent of the engine wear occurs. At 75°F the thicker oil has a viscosity in the range of 250 cS while the thinner oil has a viscosity of 100 cS. The thicker stuff is 150 cS thicker. This is a very big difference. I am using the 20W-50 as my thicker oil example here.
Found this story very interesting & educational:
Quote:
I have some stories that I collected. First, my architect drives a big SUV. He was running with Mobil 1 brand 15W-50. He changed it to Pennzoil Multi-grade (mineral oil based, non-synthetic, cheap) 5W-20 at my suggestion. His gas mileage went from 10 to 13 MPG around town. What really impressed him the most was the “robust” increase in “get up and go.” He changed from a thick synthetic to a thin mineral oil. His venue is stop and go city traffic in Florida, mostly short trips. The oil just never got that hot to require a 50 grade oil. Short trips means that the oil temperature never gets up to the normal operating range. It was too thick on short trips and too thick when it did get up to temperature.
The lower temperatures he saw with the thinner oil occurred because of reduced friction and internal drag and higher oil flow.
Quote:
Older engines may in fact benefit from thinner oil use. Over time permanent deposits of carbon and sludge build up in the engine oil ways. It is like a clogging of arteries in humans. We are now all on blood thinners.
Well, I'm convinced. No more thick oil for this Texan in the sled. I had Shell Rotella T6 15w-40 syn that had been in there for about 8k mi. I dumped in a can of BG109, increased the idle to 1300 for about 20 min., shut her off, then drained the pan AND the oil cooler. This oil came out very, very dark brown. New filter went in and I refilled with M1 0w-30. Furthermore, I'm going to shorten my OCI from 10k to 8K mi, with a filter change at 4k mi. I'll reevaluate 8k mi from now. Perhaps I'll collect a sample for an oil test.
Here's the link to Haas' article on BITOG: Motor Oil University
I've been driving Swedish turbo cars since 1983. Due to Tx heat, I've gone with thicker synthetic oils like 20W-50 or 15W-40 (with extended drain intervals of 10k mi. with an oil filter change at 5k mi.) But Haas has me rethinking this.
Don't experience deep cold here. Maybe a handfull of nights it'll hit 26F. The summers are brutal though: 105F in the shade, 120F in the sun, black asphalt at 140F. Can't remember what the thermostat is. But the coolant temp never varies from the 3 o'clock position, regardless of how hot (or how cold) it is outside.
The current sled, the Volvo, is the 2.3L, HP model. I don't put my foot in her much. Nor drive over 80mph on the freeway. Always let her warm up a bit before moving into "D". Currently at +182k mi, she doesn't burn a drop of oil.
There's too much info in his article to paste here and comment, but his points are well made. Thinner oil results in more flow which equals more cooling at a lower oil pressure.
Quote:
Increasing the pressure while using the same oil will increase the oil flow but increasing the pressure by increasing the oil thickness will result in less flow. It takes more pressure to move a thicker oil. When you go to a thicker oil the pressure goes up because of the increased resistance, and therefore reduction of flow. Because the pressure is higher sooner, the relief valve cuts in sooner. Flow will actually be less when the RPM is up and the flow is needed the most.
Didn't know this:
Quote:
The synthetic 10W-30 grade oil is based on a heavier 30 grade oil while the mineral based 10W-30 oil is based on a thinner 10 grade oil. They are both similar at operating temperatures yet the 30 grade based synthetic is actually less thick at startup and much less honey – like at low temperatures. This is the opposite of what common sense dictates.
Quote:
I truly believe that oil is much better being too thin than too thick. Over the years we have been going to thinner and thinner oils despite hotter engines with turbos and the like. The tendency is that people figure they need a 40 grade oils but then use a 50 instead. Better thinking is that if you think you need a 40, use a 30 grade oil instead. I firmly believe this based on all I know about oils.
Quote:
As it turns out synthetic oils do cling to parts better as they have higher film strength than mineral oils. Synthetics are thinner overall. They have greater slipperiness. Yet they stick better to engine parts. Again, this concept is the opposite of normal thinking.
The thickness of moving oil is measured in centiStokes or cS. Most engines want the oil viscosity to be around 10 cS at normal operating temperature. The really thick multi-grade oils have a viscosity of 20 cS at operating temperature. One is not twice as thick as the other, it is only 10 cS thicker.
As we increase the heat from 212°F to 302°F the most commonly recommended oil thins from 10 cS to 3 cS. The thicker oil drops from 20 cS to 4 cS. Note that in a very hot engine the difference between the two oils is now only 1 – 2 cS. In other words they have about the same thickness. There is little advantage to a thicker based oil as a 20W-50 at very high temperatures. No, the 4 cS oil is not twice as thick as the 2 or 3 cS oil. This difference is almost insignificant.
There is a huge advantage of using the thinner, 10W-30 at startup where 90 percent of the engine wear occurs. At 75°F the thicker oil has a viscosity in the range of 250 cS while the thinner oil has a viscosity of 100 cS. The thicker stuff is 150 cS thicker. This is a very big difference. I am using the 20W-50 as my thicker oil example here.
Found this story very interesting & educational:
Quote:
I have some stories that I collected. First, my architect drives a big SUV. He was running with Mobil 1 brand 15W-50. He changed it to Pennzoil Multi-grade (mineral oil based, non-synthetic, cheap) 5W-20 at my suggestion. His gas mileage went from 10 to 13 MPG around town. What really impressed him the most was the “robust” increase in “get up and go.” He changed from a thick synthetic to a thin mineral oil. His venue is stop and go city traffic in Florida, mostly short trips. The oil just never got that hot to require a 50 grade oil. Short trips means that the oil temperature never gets up to the normal operating range. It was too thick on short trips and too thick when it did get up to temperature.
The lower temperatures he saw with the thinner oil occurred because of reduced friction and internal drag and higher oil flow.
Quote:
Older engines may in fact benefit from thinner oil use. Over time permanent deposits of carbon and sludge build up in the engine oil ways. It is like a clogging of arteries in humans. We are now all on blood thinners.
Well, I'm convinced. No more thick oil for this Texan in the sled. I had Shell Rotella T6 15w-40 syn that had been in there for about 8k mi. I dumped in a can of BG109, increased the idle to 1300 for about 20 min., shut her off, then drained the pan AND the oil cooler. This oil came out very, very dark brown. New filter went in and I refilled with M1 0w-30. Furthermore, I'm going to shorten my OCI from 10k to 8K mi, with a filter change at 4k mi. I'll reevaluate 8k mi from now. Perhaps I'll collect a sample for an oil test.
Here's the link to Haas' article on BITOG: Motor Oil University
