Petroleum additive

[PopeyeR]

I saw several remarks about oil additives. Should your timing chain start to rattle. An effective additive will temporarily reduce noise levels. It increases the viscosity of oil. If your vehicle has accumulated 300,000 miles or more, what mileage can a fresh chain achieve? The crank gear resembles shark teeth at that point. Is a cost of 50,000 justifiable for a new chain?

[Tactical]

I do not believe an oil additive will have any effect if the chain is so worn that it is rattling.
I see no reason why it cannot get another 100,000 miles with the chain changed. The outcome is contingent upon the engine, since some need the replacement of all sprockets along with the timing system. The crank sprocket in the N47 and N57 engines is integral to the crankshaft and cannot be changed; nonetheless, I have not seen any instances of significant wear, irrespective of the mileage accrued. The first N47 had substandard sprockets due to a manufacturing issue rather than wear.

[PopeyeR]

I spoke with a BMW expert on this matter, and he said that if the vehicle has over 300,000 miles, the likelihood of the crank sprocket damaging the replacement chain is significant. If you own a motorbike with a chain that has elongated to the maximum extent permissible for adjustment. Installing a new chain may result in a lifespan of just one day. Always replace the chain in conjunction with the sprockets. No one will disclose the duration of the new chain's longevity after extensive mileage. Has anybody installed a chain on a 300,000-mile crankshaft?

[Tactical]

As previously stated, it is often not the main chain that elongates and produces the noise; rather, it is the secondary chain that engages with it.
There is no reason it cannot last 100,000 miles provided oil changes are performed regularly; but, the longevity of a chain in any engine cannot be definitively predicted, irrespective of mileage.

[Ziinsig]

I agree with Tactical; if the chain is rattling, it need replacement, and thickening the oil will not restore it to its former state, just maybe muffling the sounds. While I lack the knowledge that Johnny has with these engines, based on my observations, it seems that the noise often originates from the top chain, whilst the crank sprocket remains intact. I have seen two instances of vehicles that began to rattle after being still for many weeks. The upper chain guides were discovered to be fractured, and when kept stationary for an extended period, the oil pressure in the upper tensioner diminished, causing the guides to disintegrate. If the rattling results from the degradation of the guide rails, no additives or heavier oil can mitigate the noise, and the fragments of broken plastic guide rail will ultimately obstruct the oil pump's pickup gauze. Chains that break for the second time are often attributable to inadequate maintenance or, more commonly, the installation of inferior chain kits obtained from eBay. The mileage is contingent upon the treatment of the engine; a well maintained engine with 300,000 miles may be in superior condition compared to a neglected one with just 50,000 km. Conclusion of the essay!

[PopeyeR]

I never said that it would. It will temporarily reduce the noise. For instance, suppose you travelled from Norfolk to London by car. The chain began to produce noises; adding a can of Wynn's or STP may increase the likelihood of reaching home. No one has disclosed the mileage achievable on a new chain after 300,000 miles.

[PopeyeR]

Oil and filter are changed every 6,000 miles after the first 3,000 miles. The chain was replaced. How many miles will it last? Please do not provide an answer.

[PopeyeR]

3,000,000 miles