10w40
Thread Starter
Melting Slicks
Joined: Jan 2004
Posts: 2,746
Likes: 2
From: St. james NY
10w40
Hey guys,
Well since the last oil changed I was recommended and started using 10w40 weight oil. I have been using ROYAL PURPLE's 5w30 but used the 10w40 last oil change.
How do you guys feel about this?
Ok for a stock internal LS6. Just boltons and a 100 shot.
Thanks
Z
Well since the last oil changed I was recommended and started using 10w40 weight oil. I have been using ROYAL PURPLE's 5w30 but used the 10w40 last oil change.
How do you guys feel about this?
Ok for a stock internal LS6. Just boltons and a 100 shot.
Thanks
Z
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
My guess is that you'll make slightly more power with 5W-30 and that's what I would use vs 10W-40 unless you regularly see oil temps above 260F. Besides, engine wear will be accelerated during startup when a 10W oil is used.
Melting Slicks
Joined: Jul 2005
Posts: 2,572
Likes: 3
From: Rehoboth MA . . . NRA Life Member
St. Jude Donor '06-'07
10W40 is fine for the summer months when the temps are always above 70 degrees fahrenheit. 10W30 is recommended for temps above 0 degrees fahrenheit. I like the added protection of a slightly thicker viscosity oil when the ambient temps are 80 degrees fahrenheit and above.
I use AMSOIL 5W40 Synthetic European Formula in my 04 Z06, this covers all the range I need.
I use AMSOIL 5W40 Synthetic European Formula in my 04 Z06, this covers all the range I need.
Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
Originally Posted by CraZee ZO6
Ive just heard that 5w30 in these engines break down to fast. So the 40w would reduce engine wear..
Confused myself.
Confused myself.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Originally Posted by Dave68
More than one forum member has tracked his C5 many times with Mobile 1 5W-30 oil in the crankcase and then later on, had the oil checked. NO degradation was noted and that certainly doesn't surprise me at all. 10W oils in general do not flow as well as 0W or 5W oils at startup temperatures (even at 80 degrees F), so engine wear is worse when 10W or thicker oils are used. (According to Mobil 1 technical advisors). Mobil 1 0W-40 is an excellent oil as well, so if you normally see very high oil temps (260+), you might want to consider it as an alternative to 5W-30.
for thicker oils add an accu-sump to pre-oil the block.
we use 15-w50 in on the road ciruites do to the high heat demand. But with N, I would stick with thinner oils and just changed the oil often.
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
On the track, I routine see oil temps over 250F. In those conditions I have been using the AMSOIL SAE Synthetic High Performance 10w40 without issue. 
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