Must be a wimpy engine if 10w40 makes if feel sluggish.

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Oct 22, 2003
By Detroit
Filling it with 10w40 makes it run sluggish. I filled my wife's Aerostar 3.0 V6 with 10w40 (actually brewed it up to that with thickeners) and it really feels sluggish like there is a drag on it. On the other hand, when I switched my F150 300 cubic inch (4.9L) inline six to 10w40 I didn't notice any difference. In fact, I added a bottle of VSOT recently so am now up to about 16 cSt and still don't feel any drag. It is obvious to me that the 300 cubic inches has plenty of power to spare and so the extra drag of the thicker oil is negligible, whereas the drag is a major hinderence to the pathetic little old 183 cubic inch Aerostar.
Look at it this way, 5-10 ft lbs of torque is, as you say, much more noticeable with the smaller engine. But, there still is a loss, and why have any loss at all, if it's not necessary? Thicker doesn't mean beter protection.
Well the F150 likes the thicker oil, or so it seems. The Aerostar is going to get a load of Redline 5w20 and it will be exciting to see how much freer it runs.
Originally posted by Pablo:
10w40 (actually brewed it up to that with thickeners)
[Duh!] [I dont know] [Cool] So what is the 100° viscosity? (and cold temp as well?)

Will find out in about a month. Going to dump it at 5000 miles (longest OCI I ever did) and do analysis. This is yet another witches brew, starting with: A 11.5 cSt (approx) mix of NAPA Synthetic 10w30 and 15w50 along with half a quart Redline 10w40. Top ups (and there was 3.5 quarts worth) were: NAPA Synthetic (similar mix to above) Valvoline Synpower 5w40 Schaeffer's 132 EP Oil Treatment Durablend 10w40 Miscellaneous oil bottle drippings Pennzoil SL Synthetic 5w30 And an ounce or two of Synpower Oil Treatment Why, maybe it's the gummy polymeric mass that formed in the night from additive clash reactions. Augggggggh [Freak] Why do I do this to my engines? [freaknout] As for cold temp? Yeah man, I gotta get this stuff out of there before cold temps set in or it will be snapped distributor shaft and other ugly situations.
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