Here is a basic maintenance question. I have a Intrepid that recommends 10W-30 under normal use; however, the 5W-30 viscosity is recommended only for freezing and colder. My dealer dumped 5W-30 in it for some stupid reason. My question is do I need to get on the phone and fight them to use the correct oil or can it tolerate this for 3K miles no matter how long it takes to get to that interval.

 

Don't worry. You are fine with 5W-30W. Your engine is protected up to 30W.

Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 5W-30 as a 5W oil that will not thin more than a 30W would when hot.