Engine oil cleaning ability vs Oil temperature
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Originally Posted By: Shannow
Originally Posted By: paulri
Not sure what you mean when you say "full to saturation".... Could you explain?
Look at the video I linked, and play it backwards in your head...
As the oil cools, it's ability to hold the varnish reduces. If the oil is only holding a little bit, it might be able to stay dissolved as the temperature drops.
If the oil is holding nearly as much as it can while hot, it has to release it.
As an aside where the varnish is formed isn't necessarily where you find the deposits. e.g. on turbines, it's formed in the bearings and hydrogen seals (return oil pipes too if earthing is poor), but usually FOUND in the governor.
So like when i make myself a cup of hot chocolate and leave it in the fridge because i like it cold and the coca powder that was dissolved hot settles in the bottom? right?
Originally Posted By: paulri
Not sure what you mean when you say "full to saturation".... Could you explain?
Look at the video I linked, and play it backwards in your head...
As the oil cools, it's ability to hold the varnish reduces. If the oil is only holding a little bit, it might be able to stay dissolved as the temperature drops.
If the oil is holding nearly as much as it can while hot, it has to release it.
As an aside where the varnish is formed isn't necessarily where you find the deposits. e.g. on turbines, it's formed in the bearings and hydrogen seals (return oil pipes too if earthing is poor), but usually FOUND in the governor.
So like when i make myself a cup of hot chocolate and leave it in the fridge because i like it cold and the coca powder that was dissolved hot settles in the bottom? right?
Originally Posted By: paulri
So oil will hold varnish until it has no more capacity, and then it will lay it down on the engine.
Originally Posted By: Shannow
Yep
I have a few questions:
Is there an index for varnish holding capacity? e.g. Oil anti varnish index to compare different oil? Or does it depend on base oil + add packages, etc.?
if not, Can VOA give an idea of this capacity or what is left of it in case of UOA?
So any oil regardless of how much varnish it can hold, will deposit or "lay down" the varnish when it is cold enough to get to it's saturation point. No?
do cars in cold climates have more varnish in general? I assume based on your video, the colder it gets, the less varnish the oil can hold ... Does the rest is deposited like moisture in hot air vs. cold air or am i over-simplifying it?
Thanks
So oil will hold varnish until it has no more capacity, and then it will lay it down on the engine.
Originally Posted By: Shannow
Yep
I have a few questions:
Is there an index for varnish holding capacity? e.g. Oil anti varnish index to compare different oil? Or does it depend on base oil + add packages, etc.?
if not, Can VOA give an idea of this capacity or what is left of it in case of UOA?
So any oil regardless of how much varnish it can hold, will deposit or "lay down" the varnish when it is cold enough to get to it's saturation point. No?
do cars in cold climates have more varnish in general? I assume based on your video, the colder it gets, the less varnish the oil can hold ... Does the rest is deposited like moisture in hot air vs. cold air or am i over-simplifying it?
Thanks
When the oil gets to a point where it can no longer absorb any more combustion byproducts it begins settle and form deposits in the cooler areas of the crankcase.
Originally Posted By: Shannow
Originally Posted By: paulri
Not sure what you mean when you say "full to saturation".... Could you explain?
Look at the video I linked, and play it backwards in your head...
As the oil cools, it's ability to hold the varnish reduces. If the oil is only holding a little bit, it might be able to stay dissolved as the temperature drops.
If the oil is holding nearly as much as it can while hot, it has to release it.
As an aside where the varnish is formed isn't necessarily where you find the deposits. e.g. on turbines, it's formed in the bearings and hydrogen seals (return oil pipes too if earthing is poor), but usually FOUND in the governor.
So thats another reason to do the oilchange when the oil is very hot
Originally Posted By: paulri
Not sure what you mean when you say "full to saturation".... Could you explain?
Look at the video I linked, and play it backwards in your head...
As the oil cools, it's ability to hold the varnish reduces. If the oil is only holding a little bit, it might be able to stay dissolved as the temperature drops.
If the oil is holding nearly as much as it can while hot, it has to release it.
As an aside where the varnish is formed isn't necessarily where you find the deposits. e.g. on turbines, it's formed in the bearings and hydrogen seals (return oil pipes too if earthing is poor), but usually FOUND in the governor.
So thats another reason to do the oilchange when the oil is very hot
I'm going to revive this old thread instead of creating a new one.....my thermostat is a 160 that has been in my 76 350 Oldsmobile v8 for a few years now. I think I had a 180 before and tried the 160 when I had a temperature issue on the highway with AC on (getting over 210 after driving a while at 70+mph). Coolant flush with the machine at work fixed that issue, then I had to replace my clutch fan because it would go over 200 in traffic idling for a long time.
Now it stays almost right at 160 according to my mechanical coolant temp gauge only getting up to 165 in hot weather on longer drives or heavy traffic for a while. The Oldsmobile engines seem to warm up fast and my 7 minute stop and go commute to work in our town gets it up to 160 just as I arrive go work.
I'm thinking I should probably switch to a 180 thermostat again to aid in the oil cleaning and/or be able to extend my oil change a bit. I probably would have switched back sooner but I put headers on the car a few years ago when the gasket blew on the original manifold on one side (shouldn't have had a gasket anyway) the header is like an inch from the starter which was rebuilt about 3-4 years ago (seems like a year ago) because it started to not want to crank when hot (coincided with the the overheating from the need for a coolant flush) . The rebuilt starter has had no problems even on long trips but it's too close for comfort. I've been meaning to wrap the headers or build a heat shield of some sort but I haven't gotten around to it. I feel like the 160 thermostat has created a sort of band aid or safety cushion as far as temperature goes.
If the starter does fail again I have to drop the headers to fix it and I can't fault the local rebuilders since it's likely the heat that will do it in.
My car does short trips to work every day but does get a long drive at least once a week on average. Half an hour to an hour on the highway one way to a destination. I am wondering whether switching to a 180 thermostat will actually improve the oil performance enough to be worth any possible negative effects on the entire car such as the starter if my header wrap doesn't do the job for example. I know that most people on here will be like me and assume that 180f coolant temperature would be preferable but I'm wondering if anyone has any more concrete evidence that this is true.
Now it stays almost right at 160 according to my mechanical coolant temp gauge only getting up to 165 in hot weather on longer drives or heavy traffic for a while. The Oldsmobile engines seem to warm up fast and my 7 minute stop and go commute to work in our town gets it up to 160 just as I arrive go work.
I'm thinking I should probably switch to a 180 thermostat again to aid in the oil cleaning and/or be able to extend my oil change a bit. I probably would have switched back sooner but I put headers on the car a few years ago when the gasket blew on the original manifold on one side (shouldn't have had a gasket anyway) the header is like an inch from the starter which was rebuilt about 3-4 years ago (seems like a year ago) because it started to not want to crank when hot (coincided with the the overheating from the need for a coolant flush) . The rebuilt starter has had no problems even on long trips but it's too close for comfort. I've been meaning to wrap the headers or build a heat shield of some sort but I haven't gotten around to it. I feel like the 160 thermostat has created a sort of band aid or safety cushion as far as temperature goes.
If the starter does fail again I have to drop the headers to fix it and I can't fault the local rebuilders since it's likely the heat that will do it in.
My car does short trips to work every day but does get a long drive at least once a week on average. Half an hour to an hour on the highway one way to a destination. I am wondering whether switching to a 180 thermostat will actually improve the oil performance enough to be worth any possible negative effects on the entire car such as the starter if my header wrap doesn't do the job for example. I know that most people on here will be like me and assume that 180f coolant temperature would be preferable but I'm wondering if anyone has any more concrete evidence that this is true.
Your engine was not overheating. Go back with the 180 thermostat.
Originally Posted by ka9mnx
Your engine was not overheating. Go back with the 180 thermostat.
It would sometimes get up to 225 on the highway before the flush. It was hot but it had nothing to do with the thermostat, that was just a band aid until I figured out that all it needed was the flush (engine sat a long time - probably sediment and stuff, had to replace some leaking frost plugs).
But now that the cooling system is in good working order again I know that 180 would be the preferable thermostat temperature. As long as the starter doesn't start to get heat soaked from the headers at normal temp.
I was reminded of the need for more temperature because I recently had 2 catalysts installed because I was sick of the exhaust fumes. Now I'm worried the cats aren't getting hot enough to function properly with the temperature the engine gets up to.
Your engine was not overheating. Go back with the 180 thermostat.
It would sometimes get up to 225 on the highway before the flush. It was hot but it had nothing to do with the thermostat, that was just a band aid until I figured out that all it needed was the flush (engine sat a long time - probably sediment and stuff, had to replace some leaking frost plugs).
But now that the cooling system is in good working order again I know that 180 would be the preferable thermostat temperature. As long as the starter doesn't start to get heat soaked from the headers at normal temp.
I was reminded of the need for more temperature because I recently had 2 catalysts installed because I was sick of the exhaust fumes. Now I'm worried the cats aren't getting hot enough to function properly with the temperature the engine gets up to.
Originally Posted by caprice_2nv
Originally Posted by ka9mnx
Your engine was not overheating. Go back with the 180 thermostat.
It would sometimes get up to 225 on the highway before the flush. It was hot but it had nothing to do with the thermostat, that was just a band aid until I figured out that all it needed was the flush (engine sat a long time - probably sediment and stuff, had to replace some leaking frost plugs).
But now that the cooling system is in good working order again I know that 180 would be the preferable thermostat temperature. As long as the starter doesn't start to get heat soaked from the headers at normal temp.
I was reminded of the need for more temperature because I recently had 2 catalysts installed because I was sick of the exhaust fumes. Now I'm worried the cats aren't getting hot enough to function properly with the temperature the engine gets up to.
What does your spark curve look like with that engine?
Originally Posted by ka9mnx
Your engine was not overheating. Go back with the 180 thermostat.
It would sometimes get up to 225 on the highway before the flush. It was hot but it had nothing to do with the thermostat, that was just a band aid until I figured out that all it needed was the flush (engine sat a long time - probably sediment and stuff, had to replace some leaking frost plugs).
But now that the cooling system is in good working order again I know that 180 would be the preferable thermostat temperature. As long as the starter doesn't start to get heat soaked from the headers at normal temp.
I was reminded of the need for more temperature because I recently had 2 catalysts installed because I was sick of the exhaust fumes. Now I'm worried the cats aren't getting hot enough to function properly with the temperature the engine gets up to.
What does your spark curve look like with that engine?
Originally Posted by RDY4WAR
Originally Posted by caprice_2nv
Originally Posted by ka9mnx
Your engine was not overheating. Go back with the 180 thermostat.
It would sometimes get up to 225 on the highway before the flush. It was hot but it had nothing to do with the thermostat, that was just a band aid until I figured out that all it needed was the flush (engine sat a long time - probably sediment and stuff, had to replace some leaking frost plugs).
But now that the cooling system is in good working order again I know that 180 would be the preferable thermostat temperature. As long as the starter doesn't start to get heat soaked from the headers at normal temp.
I was reminded of the need for more temperature because I recently had 2 catalysts installed because I was sick of the exhaust fumes. Now I'm worried the cats aren't getting hot enough to function properly with the temperature the engine gets up to.
What does your spark curve look like with that engine?
Not sure, I know we recurved the hei with some cheap recurve kit about 11 years ago with different springs on the distributor. Has like 18 or 20 degrees of initial timing and something like 36 all in.
Originally Posted by caprice_2nv
Originally Posted by ka9mnx
Your engine was not overheating. Go back with the 180 thermostat.
It would sometimes get up to 225 on the highway before the flush. It was hot but it had nothing to do with the thermostat, that was just a band aid until I figured out that all it needed was the flush (engine sat a long time - probably sediment and stuff, had to replace some leaking frost plugs).
But now that the cooling system is in good working order again I know that 180 would be the preferable thermostat temperature. As long as the starter doesn't start to get heat soaked from the headers at normal temp.
I was reminded of the need for more temperature because I recently had 2 catalysts installed because I was sick of the exhaust fumes. Now I'm worried the cats aren't getting hot enough to function properly with the temperature the engine gets up to.
What does your spark curve look like with that engine?
Not sure, I know we recurved the hei with some cheap recurve kit about 11 years ago with different springs on the distributor. Has like 18 or 20 degrees of initial timing and something like 36 all in.
Ok. The timing seems good. I usually set the initial at 10-14° BTDC + 15° manifold vacuum advance for 25-29° total advance at idle. Total timing at cruise would be 40-46° depending on rpm/speed. It would then fall back on the mechanical spark curve at wide open throttle / low vacuum.
My '66 Mustang wanted to overheat into the 220-230°F when cruising on mechanical advance only with 25-30° advance at cruise rpm. I hooked up the vacuum advance and the coolant temps dropped to 190-195°F and stayed there.
My '66 Mustang wanted to overheat into the 220-230°F when cruising on mechanical advance only with 25-30° advance at cruise rpm. I hooked up the vacuum advance and the coolant temps dropped to 190-195°F and stayed there.
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