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Hi Alex,

I'm no expert when it comes to oil but some peoples ideas on this forum (not this thread) can be totally wrong. Remembering oil is a very complex item and in terms of lubrication, there are many tradeoffs from start up lubrication to hot lubrication, and the amount of heat the oil transfers around the car.

In reply to your question Alex the 10w-60 seems ok for Canberra all year round. The manual (for my car and I believe yours) says 7.5-35w oil. So a 5 or 10 weight oil when cold should be fine. The higher number (hot) can generally be as high as you want, if you are racing the 60w is when most people recommend as the oil gets very hot and as you probably know oil thins out the hotter it gets, daily driving 40 is fine as the oil never reaches really high temperatures.

I've been running Shell 5-40w but I will be using the Castrol 10-60w in Summer or for any track days.

I've never changed oil on an RB25 but it can't be as hard as the RB26. Just don't rev the engine to get the last bits of oil out :-)

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Hi Alex,

I'm no expert when it comes to oil but some peoples ideas on this forum (not this thread) can be totally wrong. Remembering oil is a very complex item and in terms of lubrication, there are many tradeoffs from start up lubrication to hot lubrication, and the amount of heat the oil transfers around the car.

In reply to your question Alex the 10w-60 seems ok for Canberra all year round. The manual (for my car and I believe yours) says 7.5-35w oil. So a 5 or 10 weight oil when cold should be fine. The higher number (hot) can generally be as high as you want, if you are racing the 60w is when most people recommend as the oil gets very hot and as you probably know oil thins out the hotter it gets, daily driving 40 is fine as the oil never reaches really high temperatures.

I've been running Shell 5-40w but I will be using the Castrol 10-60w in Summer or for any track days.

I've never changed oil on an RB25 but it can't be as hard as the RB26. Just don't rev the engine to get the last bits of oil out :-)

an important thing to note, is that while you are definitely correct in using thicker oils in racing, for daily driven purposes using too thick of an oil can be detrimental in the worst cases. certainly with cars like skylines, people want to rev the engine occasionally, however the cars may only be used for 30-40 minutes at a time. if i recall properly the best viscosity for protection at high revs is between 10-15 centistokes. for a 10w-60 oil to reach 15cs it needs to be over 120 degrees C, while 10w40 needs to be over 100degrees C. 10w40 only starts to become too thin over 120degrees.

the problem is at 90 degrees C, 10w60 oil is still 30cs and too thick for revving an engine. high engine speed and high viscosity can lead to foaming and worst of all cavitation

im not an oil expert either, im just saying its important to identify what purpose your oil needs to fulfill, racing protection or daily longevity. for my next oil change ill probably get a synthetic like 5w-40 or 0w40 as the viscosity offers more protection when the car is first started at low temperature. your current shell 5w-40 sounds like a good bet for daily use, perhaps its a good idea to put in thicker oil specifically for a track day, but run the thinner oil when you go back to daily use

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an important thing to note, is that while you are definitely correct in using thicker oils in racing, for daily driven purposes using too thick of an oil can be detrimental in the worst cases. certainly with cars like skylines, people want to rev the engine occasionally, however the cars may only be used for 30-40 minutes at a time. if i recall properly the best viscosity for protection at high revs is between 10-15 centistokes. for a 10w-60 oil to reach 15cs it needs to be over 120 degrees C, while 10w40 needs to be over 100degrees C. 10w40 only starts to become too thin over 120degrees.

the problem is at 90 degrees C, 10w60 oil is still 30cs and too thick for revving an engine. high engine speed and high viscosity can lead to foaming and worst of all cavitation

im not an oil expert either, im just saying its important to identify what purpose your oil needs to fulfill, racing protection or daily longevity. for my next oil change ill probably get a synthetic like 5w-40 or 0w40 as the viscosity offers more protection when the car is first started at low temperature. your current shell 5w-40 sounds like a good bet for daily use, perhaps its a good idea to put in thicker oil specifically for a track day, but run the thinner oil when you go back to daily use

Hey Zoomzoom sounds like he knows what he's talking about. We had to find someone who could put some science behind it.

Just remember get the oil that is classed as a fully synthetic oil and also remember that different oils of the same rated viscosity can react differently.

I remember a certain mechanic telling me the 5-40 weight oil was too light for the GTR when cold (the 5) and that was why I was having a leakage issue.

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