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Oil Viscosity Recommendation

Back in May I took my wife’s 2005 Dodge Grand Caravan for an oil change. She has always taken it herself, but she was busy getting ready for a trip. When I got home, I saw from the receipt that they had used 5W-20 oil.



According to the owner’s manual that came with the vehicle, the correct oil is 10W-30, so I went back to the shop. They pointed out that both their computer and the filler cap says 5W-20, but that they would drain what they had put in and install 10W-30 if that’s what I wanted. When I explained that my wife was going to be driving to Phoenix and then later to California across the Mojave, they allowed that 10W-30 was likely a better choice.



Curious as to the apparent discrepancy, I downloaded the 2005 Grand Caravan owners manual from the Dodge web site. Sure enough, that says that 5W-20 is recommended for all operating conditions.



I know that manufacturers have been recommending lower viscosity oils to improve their CAFE ratings, but I am willing to give up a little on gas mileage if it improves engine life. Also, we live where the temperature seldom goes below zero but where summer temperatures range into the upper 90’s. Is it prudent to use the current 5W-20 recommendation or would it be better to stick to the original 10W-30 specification?

I must agree with your 10-30 choice. Why? because I’m not certain Chrysler can build the high-precision engines needed to run happily on 20 weight oil at 100 degree desert driving conditions. The Chrysler engineering staff, who now work for Fiat, might think the automated engine assembly robots can turn out precision engines reliably and under laboratory conditions, they probably can. But when you are blazing across the Mojave, the A/C on Max Cool, the temperature gauge a little higher than “normal”, I would prefer 30 weight in the crankcase…

It’s interesting that the owner’s manual (which is normally sacrosanct) says one thing, but the online manual says another. Perhaps it’s been updated by the manufacturer?

In this instance, I’d suggest that you stick with the weight of oil that’s been used since you’ve owned the car. From the tone of your post, I’m guessing that means it’s always gotten 10W-30 oil, correct? Assuming it hasn’t given you any trouble and the gas mileage has been within spec, I’d probably continue using that weight. My opinion.

You might say that the numbers on the engine mean more than the ones in the book. Can I be sure? No, but you aren’t hurting anything with 10W30.

I have a 2003 Toyota 4Runner that calls for 5W-30 in the manual, although it says that 10W-30 may be used, but should be changed back to 5W-30 at the next oil change. A Toyota dealer did put 10W-30 in at one time and it didn’t make a difference. At another oil change at an independent shop, 5W-20 was put in instead of 5W-30. Since it was cold weather, I decided to run it until spring on the 5W-20 and there were no problems. I also have a Chevrolet Uplander that calls for 5W-30. An independent tire shop put in 10W-30 and there were no dire consequences. In your case the 10W-30 may be better than the 5W-20.

The one place where oil weight seems to be critical is in a little 1 cylinder air cooled lawnmower engine. The manual calls for 30W. I’ve known people who substituted 10W-30 and burned out the rod bearing. In the interest of science and getting out of mowing the grass, I’ve been tempted to try the 10W-30 in my mower.

Contact Chrysler and ask them why the change was made. If the first person you talk to doesn’t provide an adequate explanation, ask for a referral. Maybe you will eventually get a lubrication engineer that understands the issues and can give you and informed opinion.

what does the oil filler cap state as the oil to use?

You made the right decision; 5W20 weight oil, especially in non-synthetic will kill your engine under very hot operating conditions.

I lived in the tropics for 5 years and all the cars that used 5W30 in North Ameriuca used 20W50 there!!!.

Your best oil for both good lubrication, long life and fuel economy is 5W30 synthetic; that will give you guaranteed protection year round anywhere is the US, easy starting on a cold morning and good fuel conomy.

CAFE targets have made car manufacturers nothing short of reckless in recommending engine oils. I’m surprised that a 2005 vehicle would call for such and oil.

My 2007 Toyota came with a 5W30 spec in the owner’s manual, but I got a later bulletin from the dealer that they are now pushing 5W20.

My son’s Mazda 3 has a 5W20 spec, but he uses 0W30 Mobil 1 synthetic all year round. Yes, that same Mazda uses 20W50 or 10W30 in tropical countries without CAFE standards.

Ford did the same thing. The manuals originally called for 5W-30 and they retroactively specified 5W-20 for all or most of their engines. Increased fuel efficiency was probably the root reason for the change. The reason for retroactively specifying the 5W-20 is probably because they don?t want to ship and stock another type of motor oil.

Remember when the owner manuals used to list oils for different temps? Why don?t they have that now? The reason is probably manifold. Today?s drivers are easily confused when given that kind of choice. Oil changes are less frequent and can commonly span a couple of seasons if not 3. Lastly, the oils are better

The OP probably had the better oil in the engine for the conditions he was driving in. He is probably far more informed about vehicle maintenance since most drivers.