A couple of years ago, I had a work van that had around 140k on it. When I bought it from my boss, I asked what kind of oil he ran in it. He replied with Mobil 1 15w50. He tells me to use nothing else. Well as time rolls by, I of course forget what weight he used, so I buy 5w30 mobil 1. I noticed a difference in power big time when taking off-ramps and such. Mergeing was hell!! I did also notice that the oil pressure gauge always read a good bit higher then what I was used to on GM products, but after changing to the 5w30 it was back to around the 30 - 35 range.
A couple of weeks later, I was talking to him about it. I had dumped a bunch of money into plugs, wires, distributer cap, button, filter, cleaners all that stuff. He asked me what I used at the last oil change and I showed him a bottle of the 5w30 mobil 1. He just walked away from me. A day or two later, he reminded me of what to use. I changed the oil again the next payday and she was roaring through the streets of Tupelo, making Elvis turn over in his grave. Oh yeah, and the oil pressure was back up around 45-50.
But over all, yeah a thicker oil can do that. Is it a good thing? Well...
