radman
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Gave up being serious on this thread a while ago.
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Idle speed changed with oil change
- Thread starter Scab
- Start date
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Gave up being serious on this thread a while ago.
Tough Crowd !!
Scab, first time I have heard of this. Many on here have used different oils with no detected difference.
Interesting thing you had happen. Sounds like coincidence.
Especially since your cold (winter) number only changed by 10. :dntknw:
Scab, first time I have heard of this. Many on here have used different oils with no detected difference.
Interesting thing you had happen. Sounds like coincidence.
Especially since your cold (winter) number only changed by 10. :dntknw:
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Going to a thinner weight oil certainly reduces friction and could cause an idle speed increase. Having said that, 300 RPM seems like a lot to me to attribute to an oil viscosity change. But, I've never tried that on an FRJ so it is hard to say without some data. If you are really curious about it change the oil back and forth between the two viscosities and see if the RPM change always follows the oil viscosity. That would silence one side of the arguement immediately....LOL.
Car companies spec the 5W- and 0W- oils purely for fuel economy. On a fleet average basis there is no question that there is a substantial gain. That is really the basis for the GF3 and GF4 ratings for oils and the presence of the "starburst" symbol on the oil can that says "for gasoline engines". The GF rated oils are (by definition) fuel economy oils with friction modifiers that improve economy beyond just the viscosity reduction. So the oil makes a discernable difference in fuel economy and friction and (yes) idle speed even.
I am not sure about the idea of "tolerances being tightened" to use the lighter weight oils..... I really don't think this is true. The critical tolerances affecting oil pressure and hydrodynamic bearing film formation are basically the same as they always were. What changed as engines went to the lighter and lighter weight oils is the incorporation of rolling elements to reduce the depency on the oil film at high load points...i.e....lifters, rocker arm pivots, distributor gears, etc.... All those things have been converted to rollers (or eliminated) which are very tolerant of most any kind of lubrication.
If the story about oil filters blowing off is indeed true (sounds more like some oil filters that weren't capable of the cold pressure....hmm.....) then it could POSSIBLY be due to using the wrong viscosity oil in the engine. When the oil is cold most of the oil the oil pump is pumping is simply diverted thru the oil pump pressure regulator valve as very little flows to the engine itself. Due to the very high bypass amount when cold the bypass circuit inside the pump must be sized accordingly. Most engines have a marginally large enough bypass circuit when the oil is cold as evidenced by higher cold oil pressure indicating that the oil bypass circuit is the restriction not the oil pressure control valve. So....it is possible that if the engine had a less than marginal oil pressure bypass circuit and was filled with heavier weight oil then it could run the oil pressure out of control when the engine was revved up cold and blow the filter off. Most oil filters are designed to handle 120-130 PSI as that is not too uncommon with high revs and cold engines/oil so blowing one (or more) off is relatively uncommon. Engine development programs always incorporate checks for high RPM cold oil pressure to make sure that the bypass circuit is adequate and that (typically) cold oil pressure will not excede 100 PSI and/or the pressure limits of the system. The OEM only checks this with the recommended oil viscosity so if a different viscosity is substituted then the person doing the substitution is responsible for the results....
Even if the oil filter blowing off was an issue with that particular engine the reason that manufacturers do not like 10W40 oil in particular is because of the high levels of viscosity improvers required to meet the 10W and 40 viscosity specs. Viscosity Improver (VI) is definitely a culprit in ring belt deposits. 10W40 oils of the 70's and early 80's were notorious for high levels of VI, relatively poor quality VI packages and subsequent engine failure due to ring belt deposits from use of 10W40 oils. That is why they are still not trusted todate even though the VI packages of today are perfectly fine and do not form the deposits like the oils of yesteryear.
The comments about warmup and oil temp are true....to a point. If you look the FJR has an oil to water oil cooler on the front of the engine. Engine coolant is circulated thru the oil cooler which cools the oil when it is hot AND heats the oil up when it is cold. An oil cooler circuit like this actually warms the oil rather quickly after startup as the oil is forced to warm up at the same rate the coolant warms up. So, it is true that you need to ride the bike to get everything thoroughly up to temperature but realize that the oil temp of the FJR will be much higher than you might think on a simple garage warmup due to the oil (heater) cooler circuit.
Personally, from the parts I have seen and the evidence presented I am pretty well convinced the "tick" issue is brought on by too little lubrication of the valve guide/valve stem interface due to "too dry" of a valve stem seal. Seen it before on other engines and in other situations and all the evidence fits pretty well. Oil quality and viscosity is going to have little or no effect at all on this. A valve stem seal allows very very little oil past even on a "wet" design so changing oil viscosity or quality will just not have any effect. It would be nice if it did but it don't.....
Car companies spec the 5W- and 0W- oils purely for fuel economy. On a fleet average basis there is no question that there is a substantial gain. That is really the basis for the GF3 and GF4 ratings for oils and the presence of the "starburst" symbol on the oil can that says "for gasoline engines". The GF rated oils are (by definition) fuel economy oils with friction modifiers that improve economy beyond just the viscosity reduction. So the oil makes a discernable difference in fuel economy and friction and (yes) idle speed even.
I am not sure about the idea of "tolerances being tightened" to use the lighter weight oils..... I really don't think this is true. The critical tolerances affecting oil pressure and hydrodynamic bearing film formation are basically the same as they always were. What changed as engines went to the lighter and lighter weight oils is the incorporation of rolling elements to reduce the depency on the oil film at high load points...i.e....lifters, rocker arm pivots, distributor gears, etc.... All those things have been converted to rollers (or eliminated) which are very tolerant of most any kind of lubrication.
If the story about oil filters blowing off is indeed true (sounds more like some oil filters that weren't capable of the cold pressure....hmm.....) then it could POSSIBLY be due to using the wrong viscosity oil in the engine. When the oil is cold most of the oil the oil pump is pumping is simply diverted thru the oil pump pressure regulator valve as very little flows to the engine itself. Due to the very high bypass amount when cold the bypass circuit inside the pump must be sized accordingly. Most engines have a marginally large enough bypass circuit when the oil is cold as evidenced by higher cold oil pressure indicating that the oil bypass circuit is the restriction not the oil pressure control valve. So....it is possible that if the engine had a less than marginal oil pressure bypass circuit and was filled with heavier weight oil then it could run the oil pressure out of control when the engine was revved up cold and blow the filter off. Most oil filters are designed to handle 120-130 PSI as that is not too uncommon with high revs and cold engines/oil so blowing one (or more) off is relatively uncommon. Engine development programs always incorporate checks for high RPM cold oil pressure to make sure that the bypass circuit is adequate and that (typically) cold oil pressure will not excede 100 PSI and/or the pressure limits of the system. The OEM only checks this with the recommended oil viscosity so if a different viscosity is substituted then the person doing the substitution is responsible for the results....
Even if the oil filter blowing off was an issue with that particular engine the reason that manufacturers do not like 10W40 oil in particular is because of the high levels of viscosity improvers required to meet the 10W and 40 viscosity specs. Viscosity Improver (VI) is definitely a culprit in ring belt deposits. 10W40 oils of the 70's and early 80's were notorious for high levels of VI, relatively poor quality VI packages and subsequent engine failure due to ring belt deposits from use of 10W40 oils. That is why they are still not trusted todate even though the VI packages of today are perfectly fine and do not form the deposits like the oils of yesteryear.
The comments about warmup and oil temp are true....to a point. If you look the FJR has an oil to water oil cooler on the front of the engine. Engine coolant is circulated thru the oil cooler which cools the oil when it is hot AND heats the oil up when it is cold. An oil cooler circuit like this actually warms the oil rather quickly after startup as the oil is forced to warm up at the same rate the coolant warms up. So, it is true that you need to ride the bike to get everything thoroughly up to temperature but realize that the oil temp of the FJR will be much higher than you might think on a simple garage warmup due to the oil (heater) cooler circuit.
Personally, from the parts I have seen and the evidence presented I am pretty well convinced the "tick" issue is brought on by too little lubrication of the valve guide/valve stem interface due to "too dry" of a valve stem seal. Seen it before on other engines and in other situations and all the evidence fits pretty well. Oil quality and viscosity is going to have little or no effect at all on this. A valve stem seal allows very very little oil past even on a "wet" design so changing oil viscosity or quality will just not have any effect. It would be nice if it did but it don't.....
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Scab
I got nothin' here...
Finally. An answer to my question.
Thanks.
Thanks.
MrT
Well-known member
Why not add my 2-cents here since another FNG was asking about oil choices....
At just under 1,500 miles (which is considered past an engine's break-in period) I've changed my oil to BELRAY EXS Superbike oil which is a 0W-40. About $13 per quart. https://www.belray.com/consumer/productpages/exs.html
Years ago someone told me the biggest problem with oil breakdown is overheating, hence the argument then for good (or aftermarket) oil coolers.
One member in the thread mentioned LUCAS. At my local mechanic's strong recommendation, I've started adding one quart of Lucas Oil Additive ($15 ?) to the other 4 quarts in a big block Ford engine over 100,000 miles.
From the Oil Archives: In the early 1970's, our Honda shop used nothing but 20W-50 Castrol in all the Honda engine oil changes. First oil change was at 600 miles, then a regular interval.
At just under 1,500 miles (which is considered past an engine's break-in period) I've changed my oil to BELRAY EXS Superbike oil which is a 0W-40. About $13 per quart. https://www.belray.com/consumer/productpages/exs.html
Years ago someone told me the biggest problem with oil breakdown is overheating, hence the argument then for good (or aftermarket) oil coolers.
One member in the thread mentioned LUCAS. At my local mechanic's strong recommendation, I've started adding one quart of Lucas Oil Additive ($15 ?) to the other 4 quarts in a big block Ford engine over 100,000 miles.
From the Oil Archives: In the early 1970's, our Honda shop used nothing but 20W-50 Castrol in all the Honda engine oil changes. First oil change was at 600 miles, then a regular interval.
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