Rattling noise on cold start from the engine

[marbro]

Again, why?

What does 5W-30 actually mean?

Because the viscosity of oil changes with temperature, multigrade oils were developed to provide protection across a range of temperatures. In a 5W-30 for…

www.rymax-lubricants.com

good explanation

 

[Neuk_]

What does 5W-30 actually mean?

Because the viscosity of oil changes with temperature, multigrade oils were developed to provide protection across a range of temperatures. In a 5W-30 for…

www.rymax-lubricants.com

good explanation

Unless I missed something, 5W30 is perfectly fine for our climates, coastal and inland? My two previous cars Audi B6 A4 1.8T and Golf R, along with my wife's car, Audi Q3 2.0 TDi and my Touareg 3.0 TDI all have 5W30 as standard specification oil viscosity with minor differences in specification.

 

[airborne]

Unless I missed something, 5W30 is perfectly fine for our climates, coastal and inland? My two previous cars Audi B6 A4 1.8T and Golf R, along with my wife's car, Audi Q3 2.0 TDi and my Touareg 3.0 TDI all have 5W30 as standard specification oil viscosity with minor differences in specification.

Yea 5W30 is fine, it’s specced by many manufacturers as standard oil viscosity for their engines in Sa, maybe if you live in some insanely hot areas of South Africa you can go to 5W40 but for most people it wouldn’t be necessary.

 

[Neuk_]

Yea 5W30 is fine, it’s specced by many manufacturers as standard oil viscosity for their engines in Sa, maybe if you live in some insanely hot areas of South Africa you can go to 5W40 but for most people it wouldn’t be necessary.

That was my initial thinking, hence why I questioned it, I still want t understand why a ‘thicker’ viscosity oil is suggested for higher external temperature climates.

 

[airborne]

That was my initial thinking, hence why I questioned it, I still want t understand why a ‘thicker’ viscosity oil is suggested for higher external temperature climates.

The hotter the ambient temps the hotter the engine will run, the cooling system will eventually struggle to maintain the factory operating temps and it will hover at the upper end of that and above. Hotter temps means the oil runs thinner, to combat that you go slightly thicker on the oils hot rating 30W vs 40W.

 

[Neuk_]

The hotter the ambient temps the hotter the engine will run, the cooling system will eventually struggle to maintain the factory operating temps and it will hover at the upper end of that and above. Hotter temps means the oil runs thinner, to combat that you go slightly thicker on the oils hot rating 30W vs 40W.

From some reading I did one also has to consider start up temperature, in hotter external temperatures a ‘thicker’ oil provides better initial start up protection. I’ll chat to a friend who has studied tribology and owns a specialised lubrication business.

 

[qscwbt]

 

[airborne]

From some reading I did one also has to consider start up temperature, in hotter external temperatures a ‘thicker’ oil provides better initial start up protection. I’ll chat to a friend who has studied tribology and owns a specialised lubrication business.

Startup protection comes from the cold spec of the oil, the 5 in 5W30. Within reason the oil should be as thin as possible when the engine is started because it allows the oil to be pumped faster to all areas of the head/engine and hence better protect the engine when it is most vulnerable to wear.

The difference in speed is very telling, this Liqui Moly pic shows it well:

The 5w30 spec in oil means the oil when cold will be at the viscosity of a 5 weight oil when cold and when hot it will be at the viscosity of a 30 weight oil when hot, hence those oils are called multigrade, they give the good startup protection of a 5 weight oil that pumps easily while still giving good hot protection of a 30 weight oil.

One point to remember is when the engine is cold/at ambient temps, despite being rated at 5 weight the oil will still be a lot thicker than when it’s at the engines operating temps and acting like a 30 weight oil.

 

[Neuk_]

Startup protection comes from the cold spec of the oil, the 5 in 5W30. Within reason the oil should be as thin as possible when the engine is started because it allows the oil to be pumped faster to all areas of the head/engine and hence better protect the engine when it is most vulnerable to wear.

The difference in speed is very telling, this Liqui Moly pic shows it well:

The 5w30 spec in oil means the oil when cold will be at the viscosity of a 5 weight oil when cold and when hot it will be at the viscosity of a 30 weight oil when hot, hence those oils are called multigrade, they give the good startup protection of a 5 weight oil that pumps easily while still giving good hot protection of a 30 weight oil.

One point to remember is when the engine is cold/at ambient temps, despite being rated at 5 weight the oil will still be a lot thicker than when it’s at the engines operating temps and acting like a 30 weight oil.

Yeah, I fully understand the viscosity rating of motor oils, hence my questioning the comment 5W30 is 'too thin for our climate, especially if you live inland in winter.' which was then changed to 'summer'. Neither of which is true unless you are seeing negative 30 Deg C or 35 Deg C regularly which is quite rare in South Africa.