Little background on the car first. It is a 94 Tbird 4.6 281 SOHC with around 100k on it, can't be positive on that since about a year and a half ago the odometer stopped working around 90k.
I have a ticking noise that has been getting steadily worse especially around the 2000rpm range. I haven't noticed any loss of power and not blowing any smoke out the tailpipe. The oil gauge is fluctuating at idle and only return to normal under load. Around 65mph (1800rpm) the car is fine, increase to 70 and 2000 and the ticking returns, yet the other day I pushed the car to 80 to pass someone and the noise left again.
One mistake I made and don't know what I was thinking it that I was using a totally inadequate weight of oil in the car simply because it is free, 15w40. From what I've been able to come across I mostly likely messed up the lash adjuster using the heavier oil. I've since changed to using 5w30 but the damage may already be done. So I have come to the following conclusions..
1. Using a snake oil such as seafoam, AutoRX or kerosene to flush the engine and hopefully free up the lash adjusters without either clogging up any oil passages or filter screens.
2. Replace the lash adjusters and cam followers
I don't know if I should just try a flush and if it messes something up like clogging up the rest of the lash adjusters up, just change them at that time or could it do other damage beyond that ?
I also changed the oil pressure switch last year so I don't think that is the problem with the gauge, but may still be.
Some think it could be a timing chain issue, I'm hoping it's not that. I'm capable of changing it, since I have good help, but don't know how much a problem that is.
Would appreciate any help before I damage it any further or waste money on stuff that doesn't work or I don't need.