Oil Change???

[JPrusinows]

Guys,

Changed oil today from 10w30 Castrol GTX 8qts. to Valvoline Racing straight 40 weight 8 qts. in my maxie clone. Oil was recommended by an engine builder. Car has never ran over 185 degrees no matter what the traffic situation or weather. And yet after the oil change this morning I'm hitting 205! Last weekend 185 stop and go, this weekend 205 just taking it back to storage unit! Only thing I can think of is it has to be the oil? Going back to the Castrol tomorrow to see if this hypothesis is true. Anyone else had a similar experience? Very strange to me as I've never experienced such a big increase or decrease in heat dissipation/absorption simply from changing oil.

Thoughts? Experiences?

 

[Nate S]

I haven’t seen that in particular but I’m not surprised. Thick oil takes much more power to pump and it all goes into heat. If this required even 2 more horsepower that’s 1500w more heat to dump.

On the general purpose viscosity note, I wouldn’t run straight weight oil. Takes much longer at start up to get to all the stuff that needs it. Most of the nasty engine wear happens right at start up, don’t make it worse and last longer. 0-40 is still thicker at start up than 40 is when hot, so why do we need all that extra viscosity when cold? We don’t.

 

[Ironbuilt]

The only plus to 10w40 is the winter oil, which is what the "W" stands for. So as long as you're not in cold weather conditions, the SAE40 is fine. It actually offers better lubrication and protection in warmer temperatures.

 

[65-440]

The only plus to 10w40 is the winter oil, which is what the "W" stands for. So as long as you're not in cold weather conditions, the SAE40 is fine. It actually offers better lubrication and protection in warmer temperatures.

Huh?

 

[Nate S]

So here you go, 0-W30 vs 30. At engine temps all the same. Only difference is that the 30 will take 10-20 seconds longer to lubricate your dry engine when you start it.

In the old days prior to synthetic oil they used polymers to achieve the multi-viscosity. Oils with a big spead (10-40) could break down to a lower viscosity if you didn’t change them on time. If you want your engine to last don’t use straight weight. Probably some exceptions for race cars running many hours very hard.

 

[Hilljack68]

In the old days prior to synthetic oil they used polymers to achieve the multi-viscosity.

Were the effects of these polymers similar to ZDDP? I run Brad Penn 10W40, which has the Zinc additive. It was recommended by my engine builder.

 

[Nate S]

Were the effects of these polymers similar to ZDDP? I run Brad Penn 10W40, which has the Zinc additive. It was recommended by my engine builder.

Different thing. The polymers are long chain molecules that scrunch up when cold and stretch out when warm. On a microscopic level this increases viscosity when warm.