SAE 30
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Synthetics have a higher viscocity index, so they naturally lend themselves to winter rated oils.
So if you need the best possible lubrication, well, the "best" lubricants really aren't available in straight 30. (except amsoil, what's up with that?)
Also, cold starts are hard on engines, and obviously a 30 will take longer to reach full flow volume making them even worse.
If price and performance is an issue, then I could see a straight 30 conventional. But, in Michigan, have fun next winter!
So if you need the best possible lubrication, well, the "best" lubricants really aren't available in straight 30. (except amsoil, what's up with that?)
Also, cold starts are hard on engines, and obviously a 30 will take longer to reach full flow volume making them even worse.
If price and performance is an issue, then I could see a straight 30 conventional. But, in Michigan, have fun next winter!
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How come there's not much mention of using straight weight oils.
Because no car mfg specifies their use.
Amsoils ACD is one to consider if you are infatuated by them 8)
How come there's not much mention of using straight weight oils.
Because no car mfg specifies their use.
Amsoils ACD is one to consider if you are infatuated by them 8)
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The Viscosity index really has to do with the amount of VIs in the oil.
The proper viscosity oil should be used for the Temperatures at startup
If the proper oil is chosen for the startup temps the oil volume will be fine.
During the summer straigh 30 will be fine . Winter will bring problems with straight 30 .As the temps get too cold for the oil to travel from the sump [oil pan] to the pump think about sucking a thick milkshake through a straw it takes a long time to get to your mouth that is the cold start problem as your engine is basically running without oil. The higher wear from the metal in the engine being cold is something not worth worrying about because it just happens. You always want to run the proper viscosity range for the temps you start your car . Besides usually a multivisc oil allows the engine with proper care to outlast you ownership of the vehicle and then some with out the worry about summer oil and winter oil etc.
The proper viscosity oil should be used for the Temperatures at startup
If the proper oil is chosen for the startup temps the oil volume will be fine.
During the summer straigh 30 will be fine . Winter will bring problems with straight 30 .As the temps get too cold for the oil to travel from the sump [oil pan] to the pump think about sucking a thick milkshake through a straw it takes a long time to get to your mouth that is the cold start problem as your engine is basically running without oil. The higher wear from the metal in the engine being cold is something not worth worrying about because it just happens. You always want to run the proper viscosity range for the temps you start your car . Besides usually a multivisc oil allows the engine with proper care to outlast you ownership of the vehicle and then some with out the worry about summer oil and winter oil etc.
Subaru 2001 Legacy manual recommends #30 or #40 for severe conditions like desert driving or towing.
Thanks for the info guys..I was already aware of running straight 30 in cold temps..ie.summer equipment (lawnmower says not under 40 degrees). Anyway I bought some Havoline at WM and was going to wait until it gets warm to put it in (75-95 deg). Really was wondering why people in warm climates don't use SAE 30 year round since it has more base oil than the multi-vis oils.
Originally Posted By: Steve S
The Viscosity index really has to do with the amount of VIs in the oil.
Viscosity index is an indication of an oil's ability to resist change in viscosity with change in temp. VI has nothing to do with the amount of VI improver in the oil. The higher the VI the greater the oil's ability to resist vis change with change in temp.
The Viscosity index really has to do with the amount of VIs in the oil.
Viscosity index is an indication of an oil's ability to resist change in viscosity with change in temp. VI has nothing to do with the amount of VI improver in the oil. The higher the VI the greater the oil's ability to resist vis change with change in temp.
Originally Posted By: Warstud
Really was wondering why people in warm climates don't use SAE 30 year round since it has more base oil than the multi-vis oils.
Back in the 60s and 70s when multi-vis wasn't as good as it is now I did. I don't see any reason to do it now.
G-Man would be the one to talk to about doing it now. IIRC, he was using straight 30 weight not too long ago and may still be using it.
Really was wondering why people in warm climates don't use SAE 30 year round since it has more base oil than the multi-vis oils.
Back in the 60s and 70s when multi-vis wasn't as good as it is now I did. I don't see any reason to do it now.
G-Man would be the one to talk to about doing it now. IIRC, he was using straight 30 weight not too long ago and may still be using it.
The engine is started cold as compared to the normal running temperature of ~ 200 F. A 5w is preferred to reduce wear during the first critical 15 minutes it takes the oil to come up to temp. A cold start can be anywhere from 100 F to minus 30F.Gads that is a terrible run on sentence. It is the thought that counts.
I'd like for someone to explain how an engine wears more during cold start-up with a straight 30 compared to a 5w20. Let's assume the ambient temperature is a good 45*F, how exactly does this wear occur?
They say bearings like 4 to 100 centistokes. A 30 weight will be several hundred to several thousand at temps humans prefer, your average 30-90'F cold start. Multivis falls closer. Check the chart on main page.
Dr Haas (user AEHaas) has some thin oil articles that explain it.
It is (usually) vain to assume your conditions are so severe that the shearing at temp will ruin your stuff more than the startup process to get there.
Amsoil's advertised 30 weight could meet a multivis standard but they keep it a secret for marketing... so they sell "straight 30 weight" for the people that ask for it.
Dr Haas (user AEHaas) has some thin oil articles that explain it.
It is (usually) vain to assume your conditions are so severe that the shearing at temp will ruin your stuff more than the startup process to get there.
Amsoil's advertised 30 weight could meet a multivis standard but they keep it a secret for marketing... so they sell "straight 30 weight" for the people that ask for it.
I use DELO SAE30 in the Spring, Summer, & Fall.
The conditions at which I use it are beyond a normal vehicle's "severe service".
The conditions at which I use it are beyond a normal vehicle's "severe service".
Originally Posted By: Warstud
Thanks for the info guys..I was already aware of running straight 30 in cold temps..ie.summer equipment (lawnmower says not under 40 degrees). Anyway I bought some Havoline at WM and was going to wait until it gets warm to put it in (75-95 deg). Really was wondering why people in warm climates don't use SAE 30 year round since it has more base oil than the multi-vis oils.
I might be afraid to run a dino 30wt year round but I've run my synthetic SAE30 for over two years and over 50,000 miles. Nothing wrong with a straight 30 that also qualifies as a 10w30.
Thanks for the info guys..I was already aware of running straight 30 in cold temps..ie.summer equipment (lawnmower says not under 40 degrees). Anyway I bought some Havoline at WM and was going to wait until it gets warm to put it in (75-95 deg). Really was wondering why people in warm climates don't use SAE 30 year round since it has more base oil than the multi-vis oils.
I might be afraid to run a dino 30wt year round but I've run my synthetic SAE30 for over two years and over 50,000 miles. Nothing wrong with a straight 30 that also qualifies as a 10w30.
Strait oil is good for stationary engines that do not cold-start.
Originally Posted By: Audi Junkie
Strait oil is good for stationary engines that do not cold-start.
or Jeeps.
Strait oil is good for stationary engines that do not cold-start.
or Jeeps.
Originally Posted By: Max_Wander
I'd like for someone to explain how an engine wears more during cold start-up with a straight 30 compared to a 5w20. Let's assume the ambient temperature is a good 45*F, how exactly does this wear occur?
As an engine sits, oil drains down into the sump. Only a thin film remains at the "top" of an engine. Upon starting, a thin (5-20) will flow up and circulate much faster than a straight 30. In the time it takes the 30wt to flow, some metal-to-metal wearing has occurred. Even if its only for a few seconds, after many starts, this wear adds up.
I'd like for someone to explain how an engine wears more during cold start-up with a straight 30 compared to a 5w20. Let's assume the ambient temperature is a good 45*F, how exactly does this wear occur?
As an engine sits, oil drains down into the sump. Only a thin film remains at the "top" of an engine. Upon starting, a thin (5-20) will flow up and circulate much faster than a straight 30. In the time it takes the 30wt to flow, some metal-to-metal wearing has occurred. Even if its only for a few seconds, after many starts, this wear adds up.
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Originally Posted By: GMBoy
straight weight oil not needed when there are better multi-weight oils available. Why risk startup wear?
When used in appropriate temps, SAE30 will not cause excessive startup wear.
My '92 Wrangler trail rig was started hundreds of times in only 1200 miles of use (98% off road). It is driven through an obstacle and then shut down again until the next guy makes it. This off/on can go on throughout the day.
At the other end of the spectrum; When crawling, I spin a couple thousand RPM at only 1-2mph. This can be maintained for some time, depending on the terrain. 10W40 shears to a high 30 wt. 10W30 shears to water. SAE30 doesn't shear.
Despite these conditions, my 2.5L had single digit iron wear for that wheeling season.
straight weight oil not needed when there are better multi-weight oils available. Why risk startup wear?
When used in appropriate temps, SAE30 will not cause excessive startup wear.
My '92 Wrangler trail rig was started hundreds of times in only 1200 miles of use (98% off road). It is driven through an obstacle and then shut down again until the next guy makes it. This off/on can go on throughout the day.
At the other end of the spectrum; When crawling, I spin a couple thousand RPM at only 1-2mph. This can be maintained for some time, depending on the terrain. 10W40 shears to a high 30 wt. 10W30 shears to water. SAE30 doesn't shear.
Despite these conditions, my 2.5L had single digit iron wear for that wheeling season.
Originally Posted By: gfh77665
Originally Posted By: Max_Wander
I'd like for someone to explain how an engine wears more during cold start-up with a straight 30 compared to a 5w20. Let's assume the ambient temperature is a good 45*F, how exactly does this wear occur?
As an engine sits, oil drains down into the sump. Only a thin film remains at the "top" of an engine. Upon starting, a thin (5-20) will flow up and circulate much faster than a straight 30. In the time it takes the 30wt to flow, some metal-to-metal wearing has occurred. Even if its only for a few seconds, after many starts, this wear adds up.
Ah yes, this is the widely accepted theory. In my experiences, most cars take less than 1 second to read oil backpressure after starting. That suggests that in less than one second, all the air is out of the oil system on the delivery side. Any difference in pump up time between a 5w20 and a SAE30 would be absolutely marginal, unless the oil system is poorly designed with an oil filter mounted thread-side down or something. There was a chart from an old study that was conducted on an old Benz OM.. it showed the differences in wear among a multi-vis, straight weight across a wide range of temperatures. IIRC, straight weight not only protected better across all temperatures, but it was far more stable/consistent than the multi-vis. I wonder where that chart is?
Originally Posted By: Max_Wander
I'd like for someone to explain how an engine wears more during cold start-up with a straight 30 compared to a 5w20. Let's assume the ambient temperature is a good 45*F, how exactly does this wear occur?
As an engine sits, oil drains down into the sump. Only a thin film remains at the "top" of an engine. Upon starting, a thin (5-20) will flow up and circulate much faster than a straight 30. In the time it takes the 30wt to flow, some metal-to-metal wearing has occurred. Even if its only for a few seconds, after many starts, this wear adds up.
Ah yes, this is the widely accepted theory. In my experiences, most cars take less than 1 second to read oil backpressure after starting. That suggests that in less than one second, all the air is out of the oil system on the delivery side. Any difference in pump up time between a 5w20 and a SAE30 would be absolutely marginal, unless the oil system is poorly designed with an oil filter mounted thread-side down or something. There was a chart from an old study that was conducted on an old Benz OM.. it showed the differences in wear among a multi-vis, straight weight across a wide range of temperatures. IIRC, straight weight not only protected better across all temperatures, but it was far more stable/consistent than the multi-vis. I wonder where that chart is?
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