Can you smart folks explain this to me please!?

[bigdonniebrasco]

Ok, I'm not going to name the "brand" because it's not important, but I did my first oil change since buying this 99 Limited and I noticed some things.

I changed it myself and went from Dino 5w30 to full synthetic 5w30.

It ran great before and runs great now.

I noticed that it is running a wee bit cooler but the most interesting thing is this...

I drive the same road every day and if my cruise is set at 60 my truck ALWAYS down shifts on this big hill outside of town. After the oil change.... it doesn't downshift ... tested it 6 times.

What's the process behind that. I did nothing to the tranny.

Thanks guys.
Don

 

[stir_fry_boy]

Ok, I'm not going to name the "brand" because it's not important, but I did my first oil change since buying this 99 Limited and I noticed some things.

I changed it myself and went from Dino 5w30 to full synthetic 5w30.

It ran great before and runs great now.

I noticed that it is running a wee bit cooler but the most interesting thing is this...

I drive the same road every day and if my cruise is set at 60 my truck ALWAYS down shifts on this big hill outside of town. After the oil change.... it doesn't downshift ... tested it 6 times.

What's the process behind that. I did nothing to the tranny.

Thanks guys.
Don

Lots of factors go into horsepower (the ability to keep the vehicle at a constant speed), including air temperature, elevation, engine lubrication, gas octane level, air flow through the intake and exhaust, tire pressure etc etc.

If you didn't change anything else, the air temperature is cooler which makes air more dense providing more horsepower, and the engine is better lubricated with synthetic oil, thus easier to turn given the lower coefficient of friction providing more horsepower, and better gas mileage. I'm sure the oil is trivial but just enough for your vehicle to not have to downshift to go up that certain hill. My thinking is that it has more to do with air temperature.

 

[bigdonniebrasco]

I hear you and all of your points make perfect sense...

But the weather that day was one of the hottest so far this year by a wide margin.

Still on the same tank of gas.

Same road I have been traveling to work for 13 years. I could do it in my sleep.

Aside from the oil changed I did nothing else at all!

oh well... runs great

 

[JayRolla]

I hear you and all of your points make perfect sense...

But the weather that day was one of the hottest so far this year by a wide margin.

Still on the same tank of gas.

Same road I have been traveling to work for 13 years. I could do it in my sleep.

Aside from the oil changed I did nothing else at all!

oh well... runs great

Maybe you turned ECT off.

 

[V8Man]

Watch NASCAR. They qualify with lighter and different oils to gain horse power. At Talladega they don't touch the brakes at all because they figured that just the slight rubbing of the pads on disk takes away 10hp. So they do not set the pads, leave them open, then change all the oils and even the grease in the wheel bearings after qualifying.

 

[StreetCreeper]

Ok, I'm not going to name the "brand" because it's not important, but I did my first oil change since buying this 99 Limited and I noticed some things.

I changed it myself and went from Dino 5w30 to full synthetic 5w30.

It ran great before and runs great now.

I noticed that it is running a wee bit cooler but the most interesting thing is this...

I drive the same road every day and if my cruise is set at 60 my truck ALWAYS down shifts on this big hill outside of town. After the oil change.... it doesn't downshift ... tested it 6 times.

What's the process behind that. I did nothing to the tranny.

Thanks guys.
Don

This is what happens when you do the "Dukes of Hazzard" mod!

"Ya know, straight'nin' the curves, flat'nin' the hills..."

Well someday the mountain might get 'ya — but I bet the downshift never will.

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