Ladies and Gentlemen,

Just yesterday I purchased a used 2014 Dodge Dart Rallye with a 2.4l multiair engine from a small town used car dealer. The gentlemen said they just changed the oil(oil life 100% on dash). He said they used a full synthetic 5w-30 with dextros. Should I change this oil as soon as possible to 0w-20 full synthetic as recommended in the manual?

- Thanks for the help.

 

Part of the advantage of a 0W oil is that at cold start the oil will flow better to tighter tolerances. Cold start is where the most engine wear occurs (mostly because of no or low oil pressure, but also due to reduced cold temp flow). As the engine oil begins to warm up, it becomes thicker, and at normal operating temps, it is at it's thickest point. Using a 0W oil will get you the best lubrication at cold start because it will get into the tighter spaces in your engine and will pump better than a thicker oil when cold. I don't think it would really matter if you waited a few thousand miles, but thats up to you.

 

not so fast.
the oil does NOT get thicker as it gets hotter. that would be silly.
the thing with multi-grade oils, is they have been modified to flow differently at different temps, ie: at different temps, it has the flow characteristics of different Mono Grades.(ex:SAE 30)

also, the W stands for Winter.
the first number is the winter rating, and has to do with how cold the oil remains pumpable.
5w30 for example.
when cold, it would behave like a 5wt, but once the engine is up to temp it flows like an 30 wt.

a 5wt will pump down to around -25F(-31.6 C), while a 0wt is Good to at least -40F/C(it's the same on both scales)
but once everything is up to temp, an SAE30, 0w30,5w30,and 10w30 will all flow the same.

add to that that a synthetic will have better cold flow than a conventional of the same "weight/grade"

the other reason to go with a 0wX, over a 5wX, is a marginal increase in Fuel economy, that frankly won't amount to much for you or me, but adds up to significance across the manufacturer's "Fleet", or as you've probably heard it called, the CAFE standards [Corporate Average Fuel Economy], IE: the Government madates that the Average new vehicle a company produces has to be rated for x mpg,

it's complicated mathy stuff.

but yes, the 0w will flow more quickly at start up.

to the OP, it should really be fine. that same engine in a Fiat/Alfa/etc would likely spec a either a 5w40, or 0w40 in Europe.

 

I agree with the cold starts. I had to buy a new car due to that.

 

Yep! The oil you have is not ideal for cold starts, but it's always your choice. It's good that you asked, though, as most people do random stuff on their cars to regret later. Also, I noticed that some gas stations sell harmful products, and after that, their clients' cars are broken because of the fuel. I saw many cases like this, and the most strange I saw people who bought vehicles without experience with this topic. So, who is thinking of buying a used car check this website https://wealthtender.com/insights/mo...ng-a-used-car/ it won't be bad for beginners!

 

Oil is designed to let metal parts slide over each other on a film of oil. Synthetics are slicker and let the metal slide easier. If the OP has an engine with quite a few miles, a little heavier will compensate for a little wear. It's been a few decades since I took the course, but I seem to remember that the different numbers mean how it flows at different temperatures. 0W30 means it flows like a 0 weight oil at zero degrees Fahrenheit. The second number is it flows like a 30 weight oil at 32 degrees Fahrenheit. Now, the standards may have changed since the early 70's but it's how I remember it.

The only thing the 30 instead of the 20 will do it reduce fuel economy a little bit. The heavier weight oil should work fine otherwise. I've have extremely high mile engines that I used heavier oil to compensate for wear and got quite a few more miles out of them before replacement.