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5W20, 5W30,10W30 oil

I used 10W30 oil for the past 20 years, no matter what car I owned. Our 2004 Prius “needs” 5W30 while our 2001 Ford F150 “needs” 5W20. What happens if I don’t use those oils? If I put 5W30 in my Ford will it start having accelerator and braking issues? If I put 5W20 in our Prius will it cure it of any problems? Is one oil better in the summer or winter?

The first number 5W-10W is the winter weight of the oil. This reflects the flow characteristics of the oil below 32?.

The second number of the oil 20-30 is the flow characteristics of the oil once the engine reaches operating temperature.

The weight of the oil will not effect the engine in as far as performance.


I suggest you use the suggest oil in each vehicle. The engineers who designed the engines specified the oil necessary for the most efficient operation and the longest life.

Who knows more about each engine than the engineers who designed it?

You probably would never notice any difference with a slightly different oil, but how hard is it to use two different blends?

Agree; but if you live in the South and never encounter low temperatures, I would use 5W30 in both vehicles.

Who knows more about each engine than the engineers who designed it?

Ah …but the engineers are compelled to make a one size fits all method here in North America.

The same engine typically spec’s the same oil from the Texas panhandle to the Northwest Territories in Canada. I assure you that the one in Canada encounters times when it never even makes it to a readable state on the viscosity scale.

Now that said, I always recommend using the spec’d grade, but if one wants to reduce inventory, the differences are minor enough to work in a mostly transparent manner.

Toyota and Ford know better than you or I what kind of oil is best for each vehicle. Use what they tell you to use in the owner’s manuals.

If you check closely, your Prius owner’s manual probably says something like 5W-30 is preferred, but 10W-30 will be fine in most climates. In this case, if you don’t live in the Great White North, you can use either one.

I am willing to bet Toyota recommends synthetic oil for the Prius. If they do, you should use synthetic oil that meets Toyota’s specifications.

The same goes for your F-150. The owner’s manual probably says something like 0W-20 is preferred, but 5W-20 is acceptable in most climates.

If you put 5w30 weight in each…Nothing if the temps are moderate…but the manual writers know best so I would err on the side of caution and used separate weights for each. If you insist, I don’t think 5w30 in both would be a problem in either… I would not differ with the recommendations of the Prius. It’s a frequent start, low idle in some case motor and going above 5w on the low end would give me more concern.

Since the majority of wear on engines is at startup, I would go with 5w20, or use 5w30 in warmer climates.

on my 2004 Buick Lesabre i use 5w-30 but my manual says if needed use 10w30 no problem— in my older cars-- i always used 10w30 or 10w 40 – wonder if your manual is as generous