Does a higher KV100 number lean toward a higher HT/HS? Does a higher HT/HS lean toward a higher KV100? Or are they two totally different specs completely?
A little confused.
- Thread starter 4ever4d
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Yes, it tends to reflect the viscosity index. But not always.
Originally Posted By: 4ever4d
Does a higher KV100 number lean toward a higher HT/HS? Does a higher HT/HS lean toward a higher KV100? Or are they two totally different specs completely?
Not always. Oils that have a large dose of VII's will have high KV100, but will have lower HTHS. HTHS is the spec that you want to look at to determine an oil's ability to protect an engine at high speed and operating temperature.
Does a higher KV100 number lean toward a higher HT/HS? Does a higher HT/HS lean toward a higher KV100? Or are they two totally different specs completely?
Not always. Oils that have a large dose of VII's will have high KV100, but will have lower HTHS. HTHS is the spec that you want to look at to determine an oil's ability to protect an engine at high speed and operating temperature.
Well if you have an oil that meets for example ACEA A3/B4 it will most likely have a high Kv@100 for it's grade and a high HTHS viscosity aswell.
So if you have a high HT/HS rated oil, like some of the EURO oils that list HT/HS rates at 3.5-3.7, does that mean that the oil boundary layer will be maintained at a higher rpm range on crankshaft, rod, cam bearings, etc? Would the EURO spec oils boundary layer be greater (thicker)than with an oil rated with a 2.0-3.0 HT/HS rate if both were subject to the same rpm / temperature rate? I find it hard to believe that a lot of the European manufactured engines for the European market would have engine tolerances / operating speeds / operating temps, that vary that much from the Engines manufactured in the USA for the USA market, thus requiring the higher HT/HS spec oils for them (EURO built engines for the Euro market) versus the lower HT/HS oils spec's for our vehicles. Or, does the oil spec's we see recommended in our owners manuals just just relate to CAFE requirements?
Originally Posted By: FordCapriDriver
Well if you have an oil that meets for example ACEA A3/B4 it will most likely have a high Kv@100 for it's grade and a high HTHS viscosity aswell.
5W40 Helix Ultra is A3/B4 and has a very low Kv100 of 13.1 which is barely above the minimum for it's grade. Does that make it an exception as HTHS is 3.68
Well if you have an oil that meets for example ACEA A3/B4 it will most likely have a high Kv@100 for it's grade and a high HTHS viscosity aswell.
5W40 Helix Ultra is A3/B4 and has a very low Kv100 of 13.1 which is barely above the minimum for it's grade. Does that make it an exception as HTHS is 3.68
Originally Posted By: barryh
Originally Posted By: FordCapriDriver
Well if you have an oil that meets for example ACEA A3/B4 it will most likely have a high Kv@100 for it's grade and a high HTHS viscosity aswell.
5W40 Helix Ultra is A3/B4 and has a very low Kv100 of 13.1 which is barely above the minimum for it's grade. Does that make it an exception as HTHS is 3.68
3.68 is a good HTHS
It will stay in-grade as well, since shear stability is required for A3/B4, so no worries.
Originally Posted By: FordCapriDriver
Well if you have an oil that meets for example ACEA A3/B4 it will most likely have a high Kv@100 for it's grade and a high HTHS viscosity aswell.
5W40 Helix Ultra is A3/B4 and has a very low Kv100 of 13.1 which is barely above the minimum for it's grade. Does that make it an exception as HTHS is 3.68
3.68 is a good HTHS
It will stay in-grade as well, since shear stability is required for A3/B4, so no worries.
In the old days of monogrades KV100 and HTHS went hand in hand, more of one ment more of the other.
With Multigrade oils that use polymer viscosity index improvers (VII) it is possible to incease the KV100 a lot with only a minor increase (if any) in HTHS. This was brought under control with a J300 update that gave min HTHS requirements for various viscosity grades. It's not a real problem with modern name brand oils.
More HTHS gives more minimum oil film thickness under load at the bearings.
Euro oils like A3/B4 demand more HTHS and more TBN and more shear stability than typical American ILSAC oils. But, a typical OCI in Europe would be something like 24 months and 20,000 miles. While in America the typical OCI is 12 months and 10,000 miles.
With Multigrade oils that use polymer viscosity index improvers (VII) it is possible to incease the KV100 a lot with only a minor increase (if any) in HTHS. This was brought under control with a J300 update that gave min HTHS requirements for various viscosity grades. It's not a real problem with modern name brand oils.
More HTHS gives more minimum oil film thickness under load at the bearings.
Euro oils like A3/B4 demand more HTHS and more TBN and more shear stability than typical American ILSAC oils. But, a typical OCI in Europe would be something like 24 months and 20,000 miles. While in America the typical OCI is 12 months and 10,000 miles.
Originally Posted By: barryh
Originally Posted By: FordCapriDriver
Well if you have an oil that meets for example ACEA A3/B4 it will most likely have a high Kv@100 for it's grade and a high HTHS viscosity aswell.
5W40 Helix Ultra is A3/B4 and has a very low Kv100 of 13.1 which is barely above the minimum for it's grade. Does that make it an exception as HTHS is 3.68
A3/B4 oils from my experience typically have a viscosity high for its grade, ofcourse there are exceptions.
Originally Posted By: FordCapriDriver
Well if you have an oil that meets for example ACEA A3/B4 it will most likely have a high Kv@100 for it's grade and a high HTHS viscosity aswell.
5W40 Helix Ultra is A3/B4 and has a very low Kv100 of 13.1 which is barely above the minimum for it's grade. Does that make it an exception as HTHS is 3.68
A3/B4 oils from my experience typically have a viscosity high for its grade, ofcourse there are exceptions.
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