Jerry03GTConv

WOW!!! And there you have it on what oil to use or not to use. I know more about oil now than I ever thought existed. Thanks for all of the in-put because I read lots of pros and cons both ways on this subject. I do agree that the 5W20 oil was driven by the manufacturers to increase gas mileage. Adding tenths to the MPG when you build millions of vehicles each year is a very big deal in meeting the CAFE standards. The question on whether or not it affects engine life seems to also be driven by how religious the maintenance is done. The initial rattling on engine start-up can't be a good thing for the long haul, and as a result I will be changing to 10W30 this week to see if the rattling goes away. That being said, I again thank everyone for contributing to the issue at hand.
Jerry

racer02GTstang

i will also note that today's oils are worse than say the oils back in the 80's due to the anti-wear additives have been removed due to governement regulations.

mikemc04gt

What ?!?! Today's oils are much inproved over oils of 20 years ago, mostly due to the far superior base stocks yielded from hydroprocessing. You are correct in that some of the anti-wear addatives have been decreased, but the overall package is light years ahead.

racer02GTstang

i have been told that the SG and SH type oils are the best oils since they have some of the most anti-wear properties. i looked up in my book and those oils were made the late 80's and early 90's. this is about the mineral based oils. im sure that the synthetic processed oils have become much more advanced and better.

steve0914

everytime an oil thread comes around i fall asleep half way through it....

mikemc04gt

Today's mineral (conventional) oils that meet SM spec arenearly allhydroprocessed. They have to be to meet the spec, older group 1 solvent processed oils are too impure to meet the new spec. I'm not trying to start a running debate, just point out that even today's conventional oils with slightly weaker anti-wear addativesare very good compared to the oils of 20 years ago.

Eagle2000GT

My car is a little older than the others on this thread. Ford recommended 5w30 for the 2000 GT. Oil ratings do have something to do with viscosity as does tempature. Before multigrade oils, I drove 10 weight oil in the winter and 30 weight oil in the summer. 5 weight oil was used for very cold weather or as a breaking in oil. 40 weight oil was used for very hot tempatures or for older motors. If winter came early and the tempature dropped to near freezing with 30 weight oil still in the car, the motor did not want to turn over because of the thick oil. But the 10 weight oils lubricating power dropped to almost kerosene level during the summer's high tempatures. Multigrade oils made things a lot easier.Their viscosity remains the same over a wider range of tempatures.It will not hurt your car to run 5w30 or 10w30 during the summer because the tempature keeps the oil at a lower viscosity then it would have in the winter. I'm not sure I would recommend 10w40 unless the car is using oil.