Nissan Repair: 10w40, nissan sentra, cold temperatures

Question
I have a 1989 Nissan Sentra and I drove my car to tacoma after I went to get oil for my car and I forgot to put the oil cap back on. Came back to my friends house and started to hear dome knocking and saw some smoke coming out of my car. The oil was all over my engine. I put some 10w40 oil in my car which it takes 10w30. Is 10w40 okay for my car or should I go back to the 10w30? Will it affect my cars performance? I noticed that my heating gauge was up to about in the middle between cold and hot. What do you suggest that I do? I am worried that I have damaged the engine. My car was in good shape and it has only 15,000 miles.

Answer
Hi Cheryl -

How far did you drive? I know you went to Tacoma, but you did not mention your starting point. Once you arrived in Tacoma, how many quarts of oil did you replace in your car?

Not knowing how far (miles) you drove, I cannot be sure, but it seems that your motor is OK. In extreme cases, of course the motor would freeze up, and apparently this is not what happened. If you refilled less than 2 or 3 quarts of oil you should be fine. Your crankcase holds about 5 or 6 quarts. Also, if the knocking stopped when you put the oil in, you should also be fine. If the knocking is still there, you may have a collapsed lifter, which is bug bucks.

Also, in answer to your question, the 10/40 should be fine. In fact, due to what happened I would recommend it. The numbers mean the viscosity of the oil. The higher the number, the thicker the oil. Mutlitgrades, such as 10/40, means that at cold temperatures, the oil will be more like 10W, or flow easier so it can coat the engine parts faster. When the engine is hot, you need just the opposite, as hot oil will run like water. Hence when the engine is hot, the oil will have properties like 40W. If you live in a climate like I do, Hawaii, then you will probably only need a single grade oil. Washington State? definitely multigrade. You should change to synthetic also, next time you change oil in your car. It is expensive, but so worth it.

Hope this helps, Cheryl
aloha
calvin