Contour Enthusiasts Group Archives Forums Modifications Duratec Performance I know I'm about crucified but here it goes!

Please note that these are my observations only and only that, my opinion.

Mobile 5w-30 vs 15w-50.

Location: Southwest Florida .. cold weather..never heard of the thing.

The following was conducted over the course of a 1 1/2 months and 4 oil changes in even intervals.

oil changes.

1st: 5w-30 max pressure 25psi when hot.. notice some loss in acceleration, I thought it was everything else but my oil.. no cel..nothing..cleaned filter..etc.. process of elimanation was to go to what I did change.. oil.

2nd: 15w-50.. I definately notice my power come back..max oil pressure when hot 45-50psi, but through out the possiblity of the oil because of what a lot of people on this site have said, so I convinced myself it wasn't the oil.. even though again it was the only thing I changed.

3rd: 5w-30.. back to max 25psi and back to the decrease in acceleration.. now I start to really wonder and believe it IS the oil weight.


4th: changed it back today to 15-50 and even my girlfriend notices a "sudden" to her anyways increase in power. Torque at midrange is definately increase and oil psi in back to 40-50 area when hot.

00 svt engine has 70,000 miles on it.

I also understand the haynes manual said normal oil pressure to be 20-45psi at 1700 rpms..1700 or 1500 not sure.

Eric,
Are you still going to make the drive over here this month? I'll most likely be heading to the Auto-X session down at Metro Zoo June 28th...so if you wanna come, feel free. Otherwise, let me know if/when you wanna drive over.

Interesting observation ... too bad I just changed my oil to Mobil 1 5W30. Anyone else care to give this a shot?

but what about engine longevity,etc.....

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...

Yeah, the thicker oil sticks better to the cylinder walls which helps to seal the rings better (Lamen's terms). I've always run my Duratec on 10w-40 (I'm up North), and never any thinner, and I get better power and response too. Thicker oil also offers better protection. The reason thin oils have gotten so common these days, is because the EPA (Environmental Protection Agency) pushes thinner oil because it has less drag on moving parts (gives better fuel economy), and the oil pump doesn't take away as much HP to pump thinner oil. So cars with it use less gas over long term. Now this doesn't seem like a significant loss, and it isn't, in one car, but if everyone in the U.S. runs 5w-30, that adds up to a LOT of gas, and pollution over a year's period. But I'd rather go for the extra protection of thicker oil in my cars, and so far, it's paid off

Thicker oil with higher parasitic drag yet it felt like it had more power???

While the 50 grade oil at operating temps may not be a bad idea for extreme climates. The 15 grade (actually more like 25 at 90 degrees) is very thick to be trying to push around at startup. Greater engine wear will definitely occur.

I'd recommend a 5W40 synthetic.


The higher oil pressure does not equate to better oiling.
Also of course the oil pressure is going to go up when the viscocity of the oil is raised and raised so much.

Lubrication and sealing of rings and valve guides are what most people have in mind when running thicker oil.

They forget about the effect of oil viscosity on hydraulic lash adjusters (lifters).

As they wear, lifters cause a loss of cam duration due to increased leakdown. Thicker oil effectivly increases valve duration since the lifters pump up harder at any given RPM.