Greetings…I have a 2009 Chrysler TC with 117000 miles, a4.0/V6. From day one,
I’ve changed the oil every 5000 miles…10W30. Recently, I went to the dealer for an oil change and they put 5W30 in it. I asked why! They said it was because of the age and high mileage of the van. What do you say? They did not ask me or tell me about this change…I noticed it on the work order. Thanks…Stephen Reddy
Many believe that oil ports wear and grow, piston rings wear, and seals deteriate after a vehicle climbs up in miles. They put a heavier weight oil in to compensate for engine wear. I understand the theory, but I personally like to stick to manufacturer recommendation. Either way it doesn’t hurt.
What was Chrysler specified oil? By 2009 most mfg. specified 5W-30 or 5w-20, both for gas mileage and immediate lubrication. Rather than the 10W-30 you had previously used. But as tcmichnorth stated either way it should not hurt.
5W30 oil is thinner oil, when cold, than 10W30. Your dealer’s rationale is backwards. Normally you would switch FROM 5W30 TO 10W30 when the engine is older. Not the other way 'round.
It isn’t a problem either way as the others have indicated.
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In owners manual and on oil cap. Use what they say - probably 5W20, which is what my 2007 T&C uses.
Here’s what the Owner’s Manual states for the 4.0L engine-
Engine Oil Viscosity (SAE Grade) — 4.0L Gasoline
Engines
SAE 10W-30 engine oil is preferred for all operating
temperatures. Your engine oil filler cap also shows the
recommended engine oil viscosity for your vehicle.
It’s probably not going to do any harm in 5k miles to leave that in there until the next change. However, if it were me, I would go back and point out the Owner’s Manual and oil cap designation and tell them to re-do the oil change at their expense. If nothing more than to make the point about them deciding what was right in conflict with the vehicle manufacturer specification…
… assuming that they even stock 10w-30 at this point.
It is entirely possible that 5w-30 is all they keep on hand nowadays.
The only difference between the two oils is, the 5W-30 oil lubes the engine quicker during cold starts.
I wouldn’t worry about it.
Tester
Same here, I wouldn’t worry about it.
Hehe 
If that flies with a shop, owner will essentially receive the “engine flush” service for free.
From operation standpoint, 5W30 will have zero difference to 10W30 in summer time, this is not a race-car in the end and “hot” viscosity is “30” in both oil grades.
My 09 calls for 5-30. Older cars often called for 10-30. I guess I would go with the manual but nothing wrong with 5-30, especially on a cold day in Minnesota.
I have two issues; first, they made a judgement call without the owner’s consent and deviated from the specified oil. Those are the kind of things I personally do not appreciate when I’m paying someone to do a job. 5W30 has been around a LONG time. Way before this van was produced. This is a 2009 model year van and they went to the trouble of specifying 10W30 for the 4.0L engine specifically. Don’t know about you but I do not have enough information to second guess their reasoning for that.
Secondly, I did state it wouldn’t make much, if any, difference, especially with a 3-5k change interval. But to say there is NO difference is misleading. The wider the viscosity range of an oil, the more viscosity improvers there are per given volume. That means less actual lubricating oil. Given, not a huge difference but a difference all the same.
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It would be interesting to hear from @StephenReddy how it ended if he went to the shop to complaint.
I had a rare case where I did not do the oil change myself, and sure enough the receipt shown 5W30 in place of 0W20.
Car ran for literally few hundred feet from the car lift to the parking lot, then I did not accept the work and it immediately went back to receive a proper viscosity oil, together with some common sense into their ears from the dissatisfied customer.
That was a “free oil flush service” for me 
If they put 10W30 in place of 5W30, I would make a fuss only if it was a winter time, otherwise only marked the place for myself not to go there again.