Urgent Help Needed

[oldcarman]

Here's what I've done.

Ran the engine up to operating temperature, drove for about 40 minutes.

Wynns Engine Flush - added after the drive, car was kept idling for about 20 minutes.

Oil Change with 0w-40 - immediately after the 20 minutes, old oil was drained and replaced with Mobil 0w-40 (I was told a thinner oil may help free sticking valves)

Wynns Hydraulic Valve Lifter Treatment - added after the oil change

The above was done exactly a week ago

I've been commuting by train this week so the car has only covered about 20 miles since the oil change.

The results:
Saturday Morning - Still rough idling
Sunday Morning - No issues
Monday Morning - No issues
Monday Afternoon (after standing for 7 hours) - slight rough idle
Tuesday Morning - No issues
Wednesday Morning - No Issues
Thursday Morning - No Issues
Thursday Evening - No Issues
Friday Morning (today) - No Issues
Friday Evening (today) - slight rough idle

The results show that the rough idle has reduced significantly after the oil change, before the oil change and valve lifter treatment the car would have a very bad rough idle in the mornings which was progressively getting worse.

The oil change seems to have got things back to the way things were 4 months ago.

Although I should mention that I carried out an oil change a couple of months ago with Shell's 5W-40 - however, that oil change was done without the use of any additives and more importantly on a cold engine (big mistake).

Quite satisfied with the results so far and I hope that the rough idle goes away altogether eventually, but, only time will tell.

Massive thanks to @t-tony as this was originally his suggestion and whilst I was initially a little sceptical about an oil change fixing my problem, it was certainly the cheapest fix to try.

You didn't put a lighter oil in Faheem as the 0 is the viscosity of the oil cold and is used a lot in Canada where -40's can go on for days. The 0 makes it much easier on the oil pump to.circulate the oil on start up and as the oil warms it goes up to 40 viscosity which is likely what you were using before. For a lighter oil you could go down to a 5-30 or even a 5-20 but get it changed before the heat of summer rolls around. HTH explain it clearly JIM

 

[Faheem]

Ah @oldcarman I see. From my understanding I always thought that the first number was the weight of the oil followed by viscosity it would maintain when at operating temperature. E. G. 5w30 and 5w40 are the same weight but that 5w40 would be of a thicker consistency when the engine is warm.

So what is the difference between a lighter oil and the viscosity of it? I thought they were the same thing?! Sorry for my poor knowledge.

 

[oldcarman]

You have it now @Faheem. The oil numbers are the viscosity going from lowest to upper number and is simply a standard adapted years ago so one could match the oils needed in their climate and to their driving style. Here, a10w-40w would make the starter work very hard to turn the motor and oil pump to force oil to the upper engine. It's Clear as 100,000 mile oil coming out of an engine in globs!! JIM

 

[t-tony]

It was how the SAE (Society of Automotive Engineers) graded oil viscosity Faheem ie a 5W/40 oil was known as a 40 weight oil. I learned as an apprentice many years ago how they worked out this grading but it escapes me now. If you look into it on the internet I'm sure you'll find the answer.

Tony.