Castrol GTX 5W 30
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The GTX 5W-30 with a a 40C cSt of 62, a 100C cSt of 10.8, and a viscosity index of 168 is almost identical in this aspect to Valvoline conventional. Castrol is real stingy with any information on the product data charts and they don't give Noack, TBN, ZDDP, or other information and that bothers me but as far as thickness goes it is actually THINNER THAN I WOULD USE IN A 5W-30, conventional or synthetic, and I havn't used a conventional oil in 20 years. The viscosity index is very impressive but I fear it "may" have a lot of viscosity index improvers and "may" shear quickly.
AS far as cold flow, if you mean pumping and cranking, it has to meet the same stndards to be rated 5W as any other 5W oil so no problem there.
AS far as cold flow, if you mean pumping and cranking, it has to meet the same stndards to be rated 5W as any other 5W oil so no problem there.
Castrol fell off the GM 6094M list last year with a reformulation because it no longer met the 40,000 cP cold crank simulator requirement of it. The limits of the grade are 60,000 cP. Presently their data only rates it at the limit of 40,000 for 6094M approval.
Most conventional 5W-30 oils are in the 22,000 cP range at -35.
At temperature it may not be much thicker or thinner than similar oils, but when it gets cold it tells me that the oil is much harder to get moving than an oil such as Valvoline All-Climate.
Above 0 F it will likely not be an issue at all, but where I live it is a problem that can show itself.
Most conventional 5W-30 oils are in the 22,000 cP range at -35.
At temperature it may not be much thicker or thinner than similar oils, but when it gets cold it tells me that the oil is much harder to get moving than an oil such as Valvoline All-Climate.
Above 0 F it will likely not be an issue at all, but where I live it is a problem that can show itself.
Originally Posted By: MGregoir
At temperature it may not be much thicker or thinner than similar oils, but when it gets cold it tells me that the oil is much harder to get moving than an oil such as Valvoline All-Climate.
Above 0 F it will likely not be an issue at all, but where I live it is a problem that can show itself.
Agreed.
Valvoline has 5541cP(-30C) and GTX 6600cP(-30C) for the Cranking Viscosity.
Valvoline has 22,179(-35C) and GTX 40,000(-35C) for the Pumping Viscosity.
cP is a metric of force necessary to move a layer of liquid. So the lower the number the better.
At temperature it may not be much thicker or thinner than similar oils, but when it gets cold it tells me that the oil is much harder to get moving than an oil such as Valvoline All-Climate.
Above 0 F it will likely not be an issue at all, but where I live it is a problem that can show itself.
Agreed.
Valvoline has 5541cP(-30C) and GTX 6600cP(-30C) for the Cranking Viscosity.
Valvoline has 22,179(-35C) and GTX 40,000(-35C) for the Pumping Viscosity.
cP is a metric of force necessary to move a layer of liquid. So the lower the number the better.
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Originally Posted By: strombony
I'm not real good at interpreting the specs. Is Castrol GTX (conventional) as thin, or are it's cold-flow specs the same as Valvoline and all the other conventional brands?
I ask because I've heard talk of it being a thicker oil.
strombony,
I too would think so but since it's a conventioanl I can't say. I've never been a fan of Castrol since my college day in my Honda Accord yeilded lumpy clumps coming out of the drain pan while draining the old oil. At that time was too niev about what it was but felt something wasn't right. I use now Mobil 1 in my 89' Camry and have had good results with it and am currently trying Quaker State "Q" synthetics as a standard. NOW that Castrol is a division of BP it might be better.
Durango
I'm not real good at interpreting the specs. Is Castrol GTX (conventional) as thin, or are it's cold-flow specs the same as Valvoline and all the other conventional brands?
I ask because I've heard talk of it being a thicker oil.
strombony,
I too would think so but since it's a conventioanl I can't say. I've never been a fan of Castrol since my college day in my Honda Accord yeilded lumpy clumps coming out of the drain pan while draining the old oil. At that time was too niev about what it was but felt something wasn't right. I use now Mobil 1 in my 89' Camry and have had good results with it and am currently trying Quaker State "Q" synthetics as a standard. NOW that Castrol is a division of BP it might be better.
Durango
Originally Posted By: sunfire
Originally Posted By: MGregoir
At temperature it may not be much thicker or thinner than similar oils, but when it gets cold it tells me that the oil is much harder to get moving than an oil such as Valvoline All-Climate.
Above 0 F it will likely not be an issue at all, but where I live it is a problem that can show itself.
Agreed.
Valvoline has 5541cP(-30C) and GTX 6600cP(-30C) for the Cranking Viscosity.
Valvoline has 22,179(-35C) and GTX 40,000(-35C) for the Pumping Viscosity.
cP is a metric of force necessary to move a layer of liquid. So the lower the number the better.
Yes, but Castrol only list the MINIMUM values the oil HAS to meet; NOT the ACTUAL values the oil generates in testing. I've confirmed this in e-mails with Castrol - so no one really knows how well their oils perform in the cold - only that they will meet the minimum specs.
That being said, I get a 'feeling' that Castrols actual numbers are pretty close the minimum values allowed; b/c for years Castrol has 'specialized' in oils that are good in high heat/high stress scenarios, so they tend to blend thier oils to be 'thicker' and 'tougher' rather than 'thinner' and 'better flowing'. GTX 20w-50 has always been touted as a good oil for high-revving, high output small engines from the 1970's, and that's basically where Castrol get their 'rep' from.
Originally Posted By: MGregoir
At temperature it may not be much thicker or thinner than similar oils, but when it gets cold it tells me that the oil is much harder to get moving than an oil such as Valvoline All-Climate.
Above 0 F it will likely not be an issue at all, but where I live it is a problem that can show itself.
Agreed.
Valvoline has 5541cP(-30C) and GTX 6600cP(-30C) for the Cranking Viscosity.
Valvoline has 22,179(-35C) and GTX 40,000(-35C) for the Pumping Viscosity.
cP is a metric of force necessary to move a layer of liquid. So the lower the number the better.
Yes, but Castrol only list the MINIMUM values the oil HAS to meet; NOT the ACTUAL values the oil generates in testing. I've confirmed this in e-mails with Castrol - so no one really knows how well their oils perform in the cold - only that they will meet the minimum specs.
That being said, I get a 'feeling' that Castrols actual numbers are pretty close the minimum values allowed; b/c for years Castrol has 'specialized' in oils that are good in high heat/high stress scenarios, so they tend to blend thier oils to be 'thicker' and 'tougher' rather than 'thinner' and 'better flowing'. GTX 20w-50 has always been touted as a good oil for high-revving, high output small engines from the 1970's, and that's basically where Castrol get their 'rep' from.
Go with the Pennzoil YB 5w30. 
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