Oil Viscosity Recommendation?

I always use 5w/30 oil in winter and 10w/30 oil in summer. Now in my new vehicle, the manual recommends using 5w/20 all year round. I live in a northern climate where the temp can drop to -20 to -40 below zero in winter and can be as high as 100 to 110 in summer. Should I go by the manufacturers recommendation or should I switch between the 5w and 10w as I always have ?Oil Viscosity Recommendation?
Here is the RIGHT answer. 5W-20 ...





. The W doesn't mean WEIGHT it means WINTER...As in the viscosity at very low temps... ..then the 5W part is correct for cold temps and is necessary to lube the tiny oil galleries in newer cars in warmer weather also..


A 10W oil may not be viscous enough at start-up to lube the top of the engine at startup even in warm weather....So stick with the 5W always as recommended.


The 20 part is also necessary for the tight bearing clearances on your crankshaft etc. Again the viscosity of a 5W30 may not pump into the bearings fast enough when you fire it up.


There are engineers 100 years of auto technology going into what oil to put in the vehicle. So I would follow the specs. You have a NEW vehicle. Don't mess up your warranty experimenting with oil. Good Luck!Oil Viscosity Recommendation?
I'd go by what the manufacture says, there should be a temperature chart in the owners manual that says which temps are safe for that viscosity of oil.
It sounds like you have maybe a Ford/Mazda? Just cause they call for the grade of oil. Anyway. they test their vehicles in all sorts of climates (including a good northern central US winter of -50). And they choose the most proper grade of oil. Nowadays cars use oil flow and pressure to engage a variable valve system or other engine management systems, so using the manufacturer recommended is more important than ever.
5-w-20 is a good oil for cold climates,that would be what i would use and it being so cold out,the oil is thin enough to let the engine turn over freely when the temperatures are that cold out,you can use the same oil year around in the newer vehicles,they recommend doing this now on the newer ones,also look in the owners manual it has the proper weights of the oil in it,good luck with it.
My best suggestion would be to check with the local dealer and ask if there are any technical service bulletins concerning this issue. Don't be afraid to ask for a personal recommedation. about this also.
If it is still under warranty.Go by the manufacturers recommendation.
I live in Florida heat and run 0W-30 Amsoil synthetic


I'm guessing you have a Ford or Honda. The 20 viscosity is so auto manufacturers can meet CAFE (Corporate Average Fuel Economy) standards. I would be leary of a 20 weight oil in 100+ temperatures, unless it had the film strength and shear stability of a synthetic like Amsoil 0W-20 http://www.amsoil.com/redirect.cgi?zo=14鈥?/a>


. Synthetics perform better in extreme heat and cold and are true all-season oils. Type in your year, make, model at my website below at the Online Product Guide and look up what Amsoil synthetics are recommended for your vehicle.