10W30 But Ford Recomends 5W30..Did this do any damage..??

I've been using 10W30 for the past 2 oil changes, the ford manual on my 95 tbird v8 says 5W30 is recomended. Being that 1030 is heavier-wouldn't it be better-even in the cold?? 530 is said to be/and is lighter which makes the engine work less-but yet is recomended in cold weather..??

I thought a heavier oil would be better for all-round use, winter to summer etc..

5w30 is actually better for colder weathers; theres a chart that shows what oil works best at what temperature. right now i have 5w30 in my crx, but in the summer i switch to 10w30.

right now it is summer...or at least here in florida...lol

No you didn't do any harm. The 5W represents the viscosity of the oil when cold. A lower number in cold weather is better because it flows easier and will reach the engine parts quicker when cold. See note below also. Once it warms, it moves toward the 2nd viscosity number (30 in this case). Heavy duty or heavily abused (racing) engines use thicker oils due to the increased loads. Passenger cars use the lighter grades to get better mileage and because that's all they need. As a side note...in winter climates (think snow), it's just as important to change the oil as use the right weight. I have seen engines fail to turn over when it was 20 degrees out and the sludge they called oil actually prevented the starter from turning the oil pump!

Thanks guys.. yeah i'll probably change it to 5w30 before the 3K mark.. THANKS ALOT..

bench test, you have your viscosities backwards. the hotter the oil gets, the thinner it becomes. hence, a lower viscosity. You want a lower viscosity in the cold, the oil hasn't had time to spread through motor, as such, you want it to stay and protect the parts as long as possible. Do an oil change cold, then do an oil change hot, easiest way to support this. I would GUESS the reason why high performance motors use higher viscosity oils is in relation to the fact of the RPM's that they're running and the possiblilty of starvation to certain areas. However a thicker oil would also increase the windage within the oil pan (when the crank splashes against the standing oil in the pan) Someone formulated this for me, and I've just been to lazy to confirm it. A chevy small block turning 10k rpm (possible in them, motors that nascar runs) anyways, 1oz of oil is the slows the motor to the equivilant of 700lbs of rotating mass. I want to check this, someone have a formula I can dig into, or cross reference this? In regards to running the 10-30, you should be fine. Those motors reccommend you run a lower hot viscosity due to the clearances in the motor. Generally for daily driving you want to run lower viscosities on new motors. The clearances are so tight that its hard for the thicker oil to give proper protection. On older worn motors, a thicker oil is ok. This is from the fact that the clearances are starting to become larger and you need the thicker oil to maintain a proper oil pressure. (You want at LEAST 10PSI of oil pressure for every 1000 rpm that you're running) you should be fine, I would just go back to 5w-30 and not worry about.

Randomtask, I respectfully disagree and stand by by my post...the W is for winter. The first number is the cold flow value and the second is the hot. Rather than retyping available information, I'd suggest a search for oil viscosity.

Hmm, was confused on that, thanks for clearing it up. I'm WRONG!!!!!!!!!!

The oil gets thinner when the it gets hot. A lower SAE rating means that the oil is thinner, but note that the SAE rating are based on two different "scales". The W number does for example have requirements on pumpability, requirements on viscosity at low temperatures and the lowest viscosity allowed at 100 degC. The other rating have requirements on viscosity at 100 degC.

Modern racing engines are typically not using so thick oils, for example most NASCAR racers are using synthetic Mobil 1 0W-30. Today bearing clearences are much tighter than before and a thicker oil than needed will only reduce power output. In endurance races a thicker oil is however used, this due to that the oil becomes dilluted with fuel during the race that makes it thinner.

http://auto.howstuffworks.com/question164.htm

Sums it up, a little wierd, but we were both right bench