Breakdown

[DRG]

When oil breaks down at a certain temp has all the qualities of the oil been comprimised. Should it be changed at that point.

Thanks Dave

[Gulfstream]

By the way you formulated that question I think you know the answer...yes!

[Gary7]

Originally Posted by DRG

When oil breaks down at a certain temp has all the qualities of the oil been comprimised. Should it be changed at that point.

Thanks Dave

"Breakdown" from high oil temps is typically used to denote oxidation, and it is not a binary state, i.e., good/bad. Oxidation occurs to a greater or lesser extent over the life of the oil no matter what the operating conditions and is one of the reasons the oil has to be changed. More oxidation = more frequent oil changes. But short of coolant contamination (only possible on a V-Rod), water ingress which causes contamination, or a mechanical failure that results in particulate contamination (and if that happens, oxidation is the least of your worries), I can't think of anything that would require an immediate oil change.

If you know you had a temp spike that pushed the oil temp up excessively, you have shortened the useful life of the oil and it's probably a good idea to cut that particular change interval short. But an immediate oil change is not necessary, IMO.

[DRG]

The reason I ask is there was another thread that somebody mentioned that dino broke down at 250 and syn at 300. This seems low to me and was wondering if the oil reached these temps would it change the characteristics of the oil. Does it just change at temp or is it effected from that point on. Sorry for not explaining it better.

Dave

[Gary7]

Originally Posted by DRG

The reason I ask is there was another thread that somebody mentioned that dino broke down at 250 and syn at 300. This seems low to me and was wondering if the oil reached these temps would it change the characteristics of the oil. Does it just change at temp or is it effected from that point on. Sorry for not explaining it better.

Dave

All oil begins to oxidize as its bulk temperature increases. The higher the temp, the greater the level of oxidation. There is no threshold temp at which dino oil completely "breaks down," nor is there one for synthetics. Synthetic oils will resist oxidation at higher temps, but they too will oxidize.

An oil that never sees bulk temps over 250F will last a lot longer than oil that routinely sees temps over 250F. For an oil to suffer the least from temp related oxidation it needs to quickly get up to operating temp and always operate in a range between 150F and 250F.

[DRG]

Thanks for the info Gary.

Dave