Motor oil

Car mfg. recomrnds 5-20 weight oil. My engine has 103000 miles on it. would 5-30 weight be a better to use? Also, does mixing weights or brands of oil cause any problems?

Car mfr. recommends 5W-20 for a reason, why deviate? You might be able to use say, 10W-20 in the Summer when the oil isn’t as viscous in the morning, but again the owner’s manual should say if and when that’s o.k.

If Honda recommends 5W-20 oil, why would you want to consider anything else? Has Honda led you astray before?

Mixing brands should not cause any problems.

Mixing weights would be okay if you are mixing weights that are approved in your owner’s manual. For example, Honda recommends 5W-30 for my car, but the owner’s manual says 10W-30 is fine if I don’t live in a cold climate. Therefore, if I normally use 5W-30, but I am running a little low, and the gas station only has 10W-30, I can safely mix 5W-30 and 10W-30. However, I wouldn’t want to mix my 5W-30 oil with 20W-40 or 0W-20. That would take the overall viscosity of the oil out of the recommended range. It probably wouldn’t do any harm in the short term, and it would be okay in a pinch if I really needed oil and couldn’t get the right viscosity, but it isn’t a good idea for long term use.

The way oil viscosity ratings work, your 5W-20 oil acts like a 5 weight oil when it is cold, and it acts like a 20 weight oil when it is hot. If you were to have a mix of 50% 5W-20, and 50% 10W-30, in effect, the oil in your car would have a viscosity rating of 7.5W-25. If your owner’s manual says it is okay to use both 5W-20 and 10W-30 oil in your car, you would be fine with a 7.5W-25 mix. If the mix would take the overall viscosity rating out of the recommended range, you shouldn’t do it.

Your owner’s manual is the ultimate authority on these matters. Trust it.

Here’s a dumb question, what would you get if you mixed 2 quarts of straight 30w with 2 quarts of 10w-30. My son just saw this and asked me and I don’t know.

As to the original poster us what Honda recommends.

While it’s ok to mix brands of the same or near identical weights, don’t try and mix up your own oils, especially using single weights. Any web site recommending this is just wrong.

On a 50 degree fall day if you pour 10W oil it is pretty liquid and a quart can will empty in say 1 min. Pour a 30W quart of oil on the same day and let’s say it takes two min. to empty the can.

Now heat the oil up to about 200 degrees. Pour the quart of 10W oil and it is very liquid the can empties in say 5 seconds. Now pour the 30W oil and it takes say 20 seconds to empty the can. The 30W oil is less watery at the higher temp.

10W-30 oil pours like a 10W oil, but as the oil heats up it has the same flow as a 30W oil at normal motor operating temperature. Now lets mix 10W-30 and 30W in equal parts. You are going to have an oil that acts like 30W oil at high temperature, but at low temps the oil isn’t going to be nearly as liquid as 10W oil would be. You’ll likely have something like 20W-30 or 25W-30 oil. If it is summer you’d be ok. If it is winter and you live in International Falls, MN your oil would be too thick and would not protect your motor well upon cold start ups.

For what it’s worth, the O.P. didn’t specify what make car he or she has. My money is on Mazda.

Since we are talking about mixing a multi-weight oil with a single weight oil, I don’t know fore sure, but I think you would end up with 4 quarts of 20W-30 oil.

It’s listed in the tags, right under the original post. It is a 2005 Honda Odyssey.

Sorry, I can’t really read and write.

Manufacturer recommends ideal components. The difference in 5-20 and 5-30 in performance is negligible. It’s more important you change oil regularly, using the same brand. Mixing oil viscosity within your given range is likewise no more a problem than octane mix if your car is fine with either.

The mix would produce something like 15W-40 weight oil! But seriously, since the result is impossible to predict, these games are NOT recommended…

5W-20 in the winter, 10W-30 in the summer…