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Allan

Engine Operating Temp Increase After Changing Oil

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Allan
So two weeks ago I changed my oil because I was going to be storing my bike and it was just time it got done. Before changing it, my bike ran around 165-174 degrees when normally cruising around. It also would take a while for the engine temp to rise to the point where the radiator fan needed to kick in, when I was at stoplights and not moving. I then changed my oil myself for the first time. I followed the Yamaha service manual perfectly, used Yamalube Semi-Synthetic 10W-50 oil and immediately after doing this when I took my bike out for the "test ride" afterwards, I noticed the operating temp increased to 174-186 degrees. This is the temperature when I'm driving at a constant speed like what I observed with the temp before changing my oil. Also, it takes significantly less time for the engine to reach the point where the radiator fan needs to go on. So the bike is heating up a lot faster. I thought maybe my coolant needed to be changed, but I only have a little over 6000 miles on it, so that kind of takes that out of the equation, seeing as though the coolant is supposed to be changed at about 14,000 miles (according to the service manual). Does any one have any insight on this or have had a similar problem?

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mjh937
I am not sure that it would make that much of a difference but perhaps it was over filled before so there was more oil and that kept the engine cooler? Mine operates in the same temperature range as yours does now, so I would not worry about it. It is interesting though.

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Allan
I am not sure that it would make that much of a difference but perhaps it was over filled before so there was more oil and that kept the engine cooler? Mine operates in the same temperature range as yours does now, so I would not worry about it. It is interesting though.
My oil now is filled perfectly, so maybe that could be. I didn't check what it was before I changed it.

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snowdriftless
I wouldn't worry about it. Operating temperature between 169 (f) and 205 (f) should be acceptable. Unless your FZ is spending most of it's time +205 (f) it should be ok.
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GAZ
Unless its 45 or below I rarely see below 170s on mine. I think you should be fine.
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AlbatrossCafe
When riding my old CBR 600 in 90+ degree temps, it was common for the radiator temp to read 200+ (fan came on at 230) when the normal temp was about 175, even when going over 75mph for extended periods.
 
Without knowing how fast you were going, for how long, and outside air temp, I would agree with the two above in that it is fine.

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Allan
My normal commute is primarily on the highway doing 65-70 MPH. It normally takes me like 20-30 minutes to get there. The past few weeks the temperature has been very low, because I'm in Buffalo. I ride what ever the temp, as long as it's not raining, so the temp range is from 30-60 degrees. The really low temps like the mid 30s, this still happens. That is why I think it is weird.

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rick
My temp gauge seems to fluctuate up and down between the 174 and 178. The fan doesn't turn on until 210 or something which is hotter than I would have expected.
 
Normally, wouldn't expect an oil change to affect the temp a water cooled bike runs - after all, the thermostat determines operating temp - unless yer in slow traffic of course.
 
But one factor with the FZ is that the oil runs thru a cooler behind the oil filter. That's what that big round thing is behind the filter. That heat is given to the coolant. Could be this semi-synth oil is better at transferring heat than the dino stuff the bike is delivered with. Don't think this bike really needs a 10w50 oil, especially in Buffalo where it's not gonna be smoking hot. But still, that shouldn't be a reason.
 
Have checked the coolant level in the overflow - has that changed? Does the level in the overflow bottle get higher when the bike is hot and then come back down when it's cooled off to ambient. If that doesn't happen, you might have some air in the radiator. Open the radiator cap (cold of course and don't forget to loosen the grub screw holding the cap) and have a look inside - the level should be up near the top of the that filler tube. There's not much volume in these cooling systems, so it wouldn't take much to cause it to get a bit hotter. It would have nothing to do with the oil change of course, just a coincidence.

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Allan
@rick that was very insightful. I thought it had something to do with the coolant, because it would be the only thing that made sense. I will check the coolant levels to see if the change.

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bmwpowere36m3
I'd check the coolant level like @rick mentioned and 10W-50 is pretty heavy... not something I'd have chosen for this time of year in the Northeast. 10W-30 or 5W-40 would have been mine. I don't think its even necessary in the summer time, -40W should be sufficient. Plus the greater the viscosity spread, the more susceptible its to breaking-down/shearing out of grade due to the amount of VIIs needed.

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Allan
10W-50 is the only semi-synthetic oil viscosity that my dealer had on hand when I went to get it, and my bike desperately needed an oil change. I'm going to check the cooland levels and see what it's at.

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rick
I just did my 1st change to full synthetic - Amsoil 10w40. Amsoil is notorious for viscosities (in saybolt numbers) at the upper end of the range that describes a 10w40 or whatever oil. And yes it is a range - not all 40w oils have the same starting viscosity. Anyway, I'll keep an eye on my running temps to see if that oil change has any effect - though I'd still not expect it.
 
 

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cndnmax
180s is normal temp for me. I rarely see anything below 175 unless it's warming up of course. Running temp at 165 never. Outside temp will have a direct affect on the running temp.

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tanner68
My bike used to run at 172 and 174 when it was new. Haven't seen those temps for a few thousand miles. 178 Is about the coolest it gets. Maybe 176 on a rare moment. And it seems to heat up faster, say at a traffic light or slow traffic, than when new. My fan kicks on around 220. All this worried me at first. Now I hardly give it a thought.

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Allan
Just checked my coolant level in the little window in the over flow container, and it is very low. It only is about a centimeter from the low position. I don't know where it all went, because it was over half full when I checked it a couple of months ago. I have a container of Yamacool coolant so I will add some and see if that is the problem.

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stefano225
Last time I took my bike out with outside temp in mid 60's I was getting reading between 176/178 when moving but gradually increasing when stopped to around 186.Over the summer the fan would come on often especially this one time I was stuck in traffic for awhile with outside temp in the mid 80's.I think it's normal and all depends on outside temp and riding style as long as you keep an eye on coolant level you should be fine,like tanner68 stated I too was starting to pay to much attention then i figure it's just normal.I am still using yamalube 10w 40 since I got 3 gallons at fair price when I purchased the bike in 2014.

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rick
I'm gonna suggest you also look inside the radiator and make sure the level is up to where the overflow tube (the tube that connects the radiator to the overflow bottle) .
 
Water can slowly evaporate out of these systems, but keep an eye on the level in that overflow bottle.
 
Do you ever smell coolant when the bike is hot?
 
Gonna predict yer temps will go back to where you were used to seeing them.
 
All the variations we see from bike to bike is probably more due to sensor variations, dirt (dead critters) on radiator fins and maybe some variation from thermostat to thermostat.

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Allan
As far as I know I've never smelled coolant when the bike is hot. That being said, I don't really know what coolant smells like when it is burning out of a system... Lol I'm going to fill it and keep an eye on it. Do I just pour some coolant into the radiator fill cap until the over flow bottle shows it is at a good spot?

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bmwpowere36m3
When you opened the rad cap the fluid level was down below the seal surface?

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rick
As far as I know I've never smelled coolant when the bike is hot. That being said, I don't really know what coolant smells like when it is burning out of a system... Lol I'm going to fill it and keep an eye on it. Do I just pour some coolant into the radiator fill cap until the over flow bottle shows it is at a good spot?
It'll smell the same as it does in the bottle - sorta sweet smelling. Even if it's a very slow seep past a hose clamp, when the motor gets hot, it can usually be smelled. If you have a had a head gasket leak or worse and it was getting burned along with fuel, you'd never smell it. Hard to imagine that's happened, so let's not go there.  
The hose that connects the radiator fill tube - just beneath the metal cap - and the overflow bottle is usually just a 1/4" (6mm) or so ID. If the level in the radiator is below where that hose comes in just below the radiator cap, then fill to that hole and then close the radiator cap. Then fill the overflow bottle half way between the min and max lines. 
 
The 1st time the bike goes thru a hot and cool off cycle, what little air that's in that tube will get pushed out and you'll have a closed system again.
 
Have you checked the weep hole at the back of the water pump. If that's wet, you'll be needing a seal on the water pump. it seems to be a problem spot. It would drip to the ground and you might never notice - until the overflow bottle starts to run dry, that is.

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