Best oil to quieten a di engine down

[trannynick]

Afternoon guys. I did an oil change on my di about 4k ago, 10w/40 mannol classis semi/synth, and it has a leak from rear of rocker cover lost about half between the dipstick markers so i topped it up yesterday with some 5w30 mannol LL04 bmw spec oil, It seems to have quietened the motor right down and it seems faster, it may have just been the damp conditions but it wanted to do 65-70 a lot easier than it usually does. Could be imagining it but it certainly felt it. Anyway, looking to do another oil change over next few months and checking valve clearances when rockers off to fit new gaslet, Is there any other reccomendations for quieter running other than the old 10w/40 stuff ? Thanks.

[QuebecTransit]

I'm curious about this too. Currently running full synthetic but quite thin due to being in Canada ( it's coooooold).

Driving down to Florida and then panama later this year, so will want to run some thicker oil. Curious to hear about feedback for noise reduction.

[QuebecTransit]

I'm curious about this too. Currently running full synthetic but quite thin due to being in Canada ( it's coooooold).

Driving down to Florida and then panama later this year, so will want to run some thicker oil. Curious to hear about feedback for noise reduction.

[cherniy_chack]

Guys, oil has very little effect on the noise of the engine.
The setting of the high-pressure fuel pump and injectors has a much stronger effect on the noise and thrust of the engine. Even the clearances in the valve mechanism have little effect on engine noise compared to the setting of the pump.
There can be any oil in the engine, as long as it is there.
I am Vitaly “cherny_chak” from Kyiv, Ukraine and I have been familiar with diesel engines since childhood, and I will soon probably turn 70 years old.

[QuebecTransit]

Thanks. I'll look into the fuel pump. I've already sound proofed the hood (bonnet), doors and floor along with parts of the firewall.

[Harilaos]

Guys, oil has very little effect on the noise of the engine.
The setting of the high-pressure fuel pump and injectors has a much stronger effect on the noise and thrust of the engine. Even the clearances in the valve mechanism have little effect on engine noise compared to the setting of the pump.
There can be any oil in the engine, as long as it is there.
I am Vitaly “cherny_chak” from Kyiv, Ukraine and I have been familiar with diesel engines since childhood, and I will soon probably turn 70 years old.

I have read a lot of your posts and I understood that you really know what you say.
Recently I noticed that a neighbor's Smiley with the same intake and the same pump(Bosch) of my Transit was very quieter than mine.
How is this possible for the big difference? Is about 60-70% quieter in idle running. My non diesel mechanic reduce the advance of the pump it is quieter in idle
but the same noisy in running.

[bortaf]

timing of the diesel pump can make a differance ?