JohnnyG Posted July 25, 2009 Report Share Posted July 25, 2009 OK, I know, dangerous subject, but here we go. This thread ONLY applies to Northstar engines that recommend full sythetic motor oil. In all cases that I know of, this oil would be Mobil1. If you could buy a fully synthetic motor oil for your Northstar motor that was NOT Mobil1, and it lowered the indicated temp on your dash guage by ONE HALF A NEEDLE WIDTH, would you use it? I recently changed my oil, second time since March 2008. First with Mobil1 as recommended, with no change in operating temp, and this time with a NON Mobil product and it did just that! Lowered the engine temp! As a bonus, it slightly improved fuel economy. Furthermore, the oil was cheaper than Mobil1 in the 5 quart container. Would you like to guess the brand of the motor oil? Would you continue to use it if you had the same results? Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
JimD Posted July 25, 2009 Report Share Posted July 25, 2009 ....Would you like to guess the brand of the motor oil?SuperTech. Would you continue to use it if you had the same results?I'll disqualify myself here 'cause my engine is spec'd for dino oil. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
Texas Jim Posted July 25, 2009 Report Share Posted July 25, 2009 If results are as posted... Just my opinion...but, YES...I would continue ro use it Link to comment Share on other sites More sharing options...
OynxSTS Posted July 25, 2009 Report Share Posted July 25, 2009 Probably not... any and every time my temp needle isn't perfectly straight up I get tense... Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
JohnnyG Posted July 25, 2009 Author Report Share Posted July 25, 2009 Probably not... any and every time my temp needle isn't perfectly straight up I get tense... I heard THAT! But now that the new car's needle points to the side, I feel a little better about the whole thing. I had my doubts that this would be possible, giving the fact that the engine's temp is controlled by a thermostat and all, but I did observe these results. The oil is Pennzoil Platinum. In the proper grade for my car, 5W-30. I've actually held off on posting about this, and the magnetic drain plug that I made, for a couple of months just to see if the temp held lower during the heat of summer. So far it has, and rock steady as with most Northstar engines. I know it's not much difference, I mean 1/2 a needle width isn't a lot, but with thermostat control I wouldn't expect more variation than that. Something's going on, and if anybody has any theories, other than the obvious, I'd like to hear them. 5 quart jugs of Penzoil Platinum were selling a WM for $20.00 while Mobil1 was selling for $26.00, when you can save $12.00 and have enough oil for a year I'd say it's a pretty good deal. Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
Ranger Posted July 25, 2009 Report Share Posted July 25, 2009 I might use it for the fuel savings, but not for the temperature because I don't consider 12:00 a problem or left of 12:00 a benefit. Link to comment Share on other sites More sharing options...
OynxSTS Posted July 25, 2009 Report Share Posted July 25, 2009 I might use it for the fuel savings, but not for the temperature because I don't consider 12:00 a problem or left of 12:00 a benefit. Happiness is a 12:00 needle. Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
joeb Posted July 26, 2009 Report Share Posted July 26, 2009 what do you think is wrong with your thermostat that it can't maintain the normal engine temp? sticking open? Link to comment Share on other sites More sharing options...
Jan Olsson Posted July 26, 2009 Report Share Posted July 26, 2009 OK, I know, dangerous subject, but here we go. This thread ONLY applies to Northstar engines that recommend full sythetic motor oil. In all cases that I know of, this oil would be Mobil1. If you could buy a fully synthetic motor oil for your Northstar motor that was NOT Mobil1, and it lowered the indicated temp on your dash guage by ONE HALF A NEEDLE WIDTH, would you use it? I recently changed my oil, second time since March 2008. First with Mobil1 as recommended, with no change in operating temp, and this time with a NON Mobil product and it did just that! Lowered the engine temp! As a bonus, it slightly improved fuel economy. Furthermore, the oil was cheaper than Mobil1 in the 5 quart container. Would you like to guess the brand of the motor oil? Would you continue to use it if you had the same results? I don't have a Northstar without engine oil cooler (synthetic oil recommended) but I'll answer this one anyway.... Half a needle equals what? 5F? My guess is that you have a problem with your temp gauge, thermostat or drove more carefully than usual. You are aware of the dampening in the temp gauge that makes the needle point straight up even when slightly warmer or cooler? Thats made just not to alarm owners who thinks there is something wrong with a fluctuating gauge... The engine encounter more thermal cycling when you are warming it up from a cold start Link to comment Share on other sites More sharing options...
JohnnyG Posted July 27, 2009 Author Report Share Posted July 27, 2009 what do you think is wrong with your thermostat that it can't maintain the normal engine temp? sticking open? Ahhh! The seed of doubt! Beautiful! Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
Jan Olsson Posted July 28, 2009 Report Share Posted July 28, 2009 what do you think is wrong with your thermostat that it can't maintain the normal engine temp? sticking open? Ahhh! The seed of doubt! Beautiful! You know that the thermostat's purpose is to maintain a desired engine temperature whether you drive hard or like an old fart? Sounds like snake oil to me... Link to comment Share on other sites More sharing options...
MadeInAmerica Posted July 30, 2009 Report Share Posted July 30, 2009 If you could buy a fully synthetic motor oil for your Northstar motor that was NOT Mobil1, and it lowered the indicated temp on your dash guage by ONE HALF A NEEDLE WIDTH, would you use it? Hi JohnnyG. When you say, "indicated temp", I assume you mean, coolant temperature, correct? I haven't seen any Cadillac with an oil temperature gauge, so I think you must mean the coolant temperature gauge? The coolant temperature is controlled by the thermostat and many of these are set for 195 deg. F. In other words, when the coolant temperature reaches 195 deg. F. inside the engine, the thermostat opens, allows the hot coolant to flow from the engine to the radiator via the upper radiator hose, with cool air flowing through the radiator, dispersing the high coolant temperatures and then returning the coolant to the engine via the lower radiator hose and the process starts all over again, thus keeping the coolant temperatures at 195 deg. F. When the coolant is below 195 deg. F., (i.e. when the engine is cold and being started for the first time of the day), then the thermostat stays closed until the coolant temperature reaches 195 deg. F. and then it will open, etc. In this manner, the thermostat controls the coolant temperatures. The thermostat opens and closes repeatedly to keep the coolant operating at the correct temperature for the best engine wear, fuel economy, power, lower emissions, etc. I wholeheartedly agree that a quality PAO based Group IV synthetic oil will reduce engine operating temperatures, (as has been exhaustively documented for many years from a plethora of independent sources), however coolant temperatures are not engine operating temperatures. Engine operating temperatures are the temperature of the engine parts that are not cooled by the cooling system, which only cools the upper portion of the engine. The lower end of the engine, i.e. crankshaft, connecting rods, pistons, bearings, timing chain(s), etc., are cooled by the engine oil and this temperature is reflected in the temperature indicated on an engine oil temperature gauge. If your coolant temperature is lower after an oil change, this would seem to indicate a coincidental thermostat failure, (with the thermostat sticking open all the time, over-cooling the coolant, which is not desirable), and/or a coolant temperature gauge or temperature sensor beginning to fail. Link to comment Share on other sites More sharing options...
MadeInAmerica Posted July 30, 2009 Report Share Posted July 30, 2009 5 quart jugs of Penzoil Platinum were selling a WM for $20.00 while Mobil1 was selling for $26.00, when you can save $12.00 and have enough oil for a year I'd say it's a pretty good deal. How do two five quart jugs last a year, or was that just a typo? Link to comment Share on other sites More sharing options...
JimD Posted July 30, 2009 Report Share Posted July 30, 2009 .... In other words, when the coolant temperature reaches 195 deg. F. inside the engine, the thermostat opens, allows the hot coolant to flow from the engine to the radiator via the upper radiator hose, with cool air flowing through the radiator, dispersing the high coolant temperatures and then returning the coolant to the engine via the lower radiator hose and the process starts all over again, thus keeping the coolant temperatures at 195 deg. F. Not quite that way for a Northstar engine. Allow me to nitpick a little since this thread is drifting off-topic. The thermostat in the cooling system is specified to be fully open at 185 degrees F. (2004 Deville Service Manual, pg. 6-14). The reason for displayed coolant temperatures to level-off at values closer to 200 degrees F. is because of the location of the coolant temperature sensor relative to the thermostat. Above you accurately described the flow of coolant in liquid cooled engines using an "outlet-side" thermostat location. However, the Northstar cooling system is designed as an "inlet-side" thermostat location. End of nitpicking. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
MadeInAmerica Posted July 30, 2009 Report Share Posted July 30, 2009 Hi JimD. The point of my post was that the oil brand or type doesn't affect coolant temperatures that the original poster had noted, so it was indeed right on topic. Link to comment Share on other sites More sharing options...
MadeInAmerica Posted July 30, 2009 Report Share Posted July 30, 2009 I'll disqualify myself here 'cause my engine is spec'd for dino oil. Hi JimD. What kind of engine would that be? I've never heard of this before. Link to comment Share on other sites More sharing options...
JimD Posted July 30, 2009 Report Share Posted July 30, 2009 And contained inaccurate information that I challenged for the benefit of future readers. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
MadeInAmerica Posted July 30, 2009 Report Share Posted July 30, 2009 And contained inaccurate information that I challenged for the benefit of future readers. Pardon??? Link to comment Share on other sites More sharing options...
JohnnyG Posted July 31, 2009 Author Report Share Posted July 31, 2009 How do two five quart jugs last a year, or was that just a typo? You sound familiar somehow, but we won't get into that right now. Thanks for your explanation on thermostat operation. it was rather in depth. I didn't red JimD's exception to your comments at this point, so I'll leave that for another time too. Now for the quote above: I purchased my 2008 DTS in March 2008. Even though I changed the oil filter several times, and the engine oil once, I did not reset the oil life indicator in order the determine just how many miles it would go before calling for a change. When it went past 12,500 miles, and had 32% oil life left, I decided it would exceed the time period that I would be comfortable with IN MY TYPE OF DRIVING. (100% highway). I then fell back on the service interval recommendations in the owners manual.....12 months. Therfore in MY TYPE OF DRIVING, an oil purchase of two 5 quart jugs, with 2.5 quarts left over to add, should I ever need to add any, would be equivalent to a one years supply of motor oil...10 quarts. Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
JohnnyG Posted July 31, 2009 Author Report Share Posted July 31, 2009 Just read JimD's post. From his remarks, it seems to me that for the Northstar, a reduction in internal engine friction could possibly reduce coolant temperature, or at least the indicated value SLIGHTLY. Keep in mind that I'm only talking about a very small amount of needle variation here, less than a needle's width, so we're not talking about stuck thermostats or anything of that nature. This is at highway speed, 3-4 hours on the road, needle steady, indicating just a little bit lower than with Mobil1. Oh yeah, I am talking coolant temp, not oil temp, though I agree that oil temp would be a better indicator......maybe someday I'll put one on. Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
MadeInAmerica Posted July 31, 2009 Report Share Posted July 31, 2009 Just read JimD's post. From his remarks, it seems to me that for the Northstar, a reduction in internal engine friction could possibly reduce coolant temperature, or at least the indicated value SLIGHTLY. Keep in mind that I'm only talking about a very small amount of needle variation here, less than a needle's width, so we're not talking about stuck thermostats or anything of that nature. This is at highway speed, 3-4 hours on the road, needle steady, indicating just a little bit lower than with Mobil1. Oh yeah, I am talking coolant temp, not oil temp, though I agree that oil temp would be a better indicator......maybe someday I'll put one on. My point was that regardless of coolant system design, the temperature is controlled by the thermostat and not anything else, like oil type, etc. Link to comment Share on other sites More sharing options...
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