I helped my friend change his engine oil, trans oil, and diffy oil the other day and is now having a strange noise. We added Auto-rx as well. He made a post on Miata.net about the details, I will copy and paste it here. What do you think the problem is? Do you think the Auto-rx caused it? I think he added a bottle of Techron as well. The new oil filter is a Purolator Premium Plus.
quote:
Hello everyone, I changed the engine/transmission/differential oil yesterday and noticed a few differences this morning. I used Castrol GTX 10W-30 with a Purolator oil filter for the engine, Redline MT-90 for the transmission and Redline 75W-90 for the differential. I previously had Pennzoil 10W-30 with a Pennzoil filter. The car has used many different brands of oil filters and never had any problems during my ownership. First of all, when I started the car up, I heard a noise I hadn't heard before. Hard to describe, but it sounded like a scratchy-tapping noise coming from the engine bay, maybe the timing belt? Not quite sure. It didn't go away after warming the car up for a couple minutes, but it did go away after driving ~20 miles. Secondly, the idle would dip below the normal idling (about 800) rpm when coming to a stop or shifting out of gear and into neutral. Before the oil change, when I'd shift into neutral, the tach would drop to 800 rpm and stay there. Now it drops to about 500 rpm then goes back to 800 rpm, where it stays. Lastly, I noticed another new noise, this one more of the buzzing type, starting from 3500 rpm and fading away above 4500. Well it may either be fading away or I might just not be hearing it because the engine's just louder above 4500. This one was more difficult to notice, or maybe I'm just paranoid. I only noticed this when cold also. One thing of note is that I went for a sprited drive immediately after the oil change yesterday, and the car seemed great. All these symptoms surfaced this morning. I searched through many threads regarding idle dip and noise, but I wanted to ask because I couldn't find a case of all three symptoms appearing together, and especially since these appeared right after I changed the oil. I do believe changing the oil had something to do with it because chances are low that there are three different culprits that decided to rear their ugly heads at the same time. Any help would be much appreciated!! Danny
