What is considered (cold start ) temp?

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Where i live, it doesn't drop below 30*f.

In the summer, its constantly 100f to 123f for 4 months straight.

So what would be considered cold for hdeo oils ? Do i need worry cold starts?
 
With HDEO is assume you mean a 15W-40 HDEO?
I would personally not use 15W-40 in temps below -10C ( +15F ) unless the engine was plugged in with a heater, at those temperatures however i would probably choose a full synthetic 5W-40 though.

So if it doesn't go below freezing where you live you should be ok with a 15W-40 HDEO all year.

I've started my car with 20W-50 in the sump at slightly below freezing without issues, although ofcourse being very gentle and being careful not to rev the engine too much for the first few minutes of running.
 
Originally Posted By: aquariuscsm
I consider "cold "starts" the very first of the day startups.


I agree with the above as far as the engine is concerned. Pistons have to reach operating temperature of 400 to 500 F to expand into their design shape and dimensions. Engines should be operated gently until these clearances are established. You will not have any problem with 15W-40 HDEO pumpability at your temperatures, but it is still a good idea to drive gently until oil temperature is above roughly 160F so that there is no chance of the oil filter by-pass valve opening at high RPM's with higher viscosity oil. Even if the coolant temperature gauge reads on the dial when first started, the engine is not really warmed up until it operates for 5 minutes in hot ambient temperatures or 10 minutes in cold temperatures.
 
Originally Posted By: leroyd92
Where i live, it doesn't drop below 30*f.

In the summer, its constantly 100f to 123f for 4 months straight.

So what would be considered cold for hdeo oils ? Do i need worry cold starts?


For you, 30°F.

No you don't need to worry, even with a 15wxx oil.
 
i know several people that use a straight grade oil in PHX year round. some use 30, some 40, no issues.
 
I assume you mean temps that make starting harder on the engine due to the cold. For me -5F is around the temp where a conventional 5w30 shows cold starting problems relative to synthetic.

At -15F it starts to get really pronounced. I used Maxlife 5w30 blend for years, and got a horrible shaking on -15 startups. I got "mayonnaise" in the oil cap all winter from mixing the oil with condensation.

Then I went to 5w30 PP, and all those issues went away. Smooth starts at -25F and never any mayonnaise in the oil cap.

In AZ, you would not need to worry, unless you run 20w50 or something like that and it got to 10F. Even 10w40 would be fine all year in AZ.
 
Any start below operating temperature is a "Cold Start" as referred to in automotive literature, service documents, or oil specifications. If it's a specific reference to the environment the engine is operated in, they will state it as " hot/warm/cool/cold etc. ambient temperature".
 
Lived in Fargo ND back in the late 90's for 2 winters and had a 94 Camry that ran Napa 5w30 started easily and many many days were below zero and a few days would reach the -20s but then again 4 bangers tend to start easier than the big V8's. Saw many big V8s struggle to start in minus temps .. probably due more to weak battery rather than oil. Now in Nebraska and we get very few below zero days but do get a few.. have had zero issues with my current vehicles using 5w20 conventional oil. Temps above 30f are certainly not going to be an issue.
 
The connotation of "cold start" is more along the lines of "colder than the oil's normal operating temperature". It's not necessarily referring to the ambient temperature of the air. Even if the ambient temp is 100 F, that's still way lower than the usual ~190-200F most oil sumps operate at. The oil will be much thicker at 100F and hence wear is increased.
 
Any start below an oil temp of approx 165-175 deg F is a cold start, at least from the standpoint of the engine producing and accumulating corrosion products. Once at normal oil temps 175-185 deg F the "damage" from cold starting/warm up is essentially over.

The car mfg's test their engines & oils in the 130-150 deg (oil temp) corrosion range for X number of hours to see how well the oil holds up. At colder temps the oil's cold viscosity is supplying a strong benefit. Once that's gone, and before normal oil temps, and before the oil's add package is fully functional when hot, is the range of 130-150 deg that you want to minimize. To me, cold start means conditions ripe for engine corrosion and wear.
 
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