8.1L V8 - oil black after 20hrs of use. Normal ?

R

ringmaster

Joined
Dec 5, 2004
Messages
270
Location
North
2007 MasterCraft boat with GM Vortec Indmar 8.1L L18 running Valvoline VR1 Racing SAE 40 High Performance High Zinc oil.

I paid a shop to do a seasonal oil change with the VR1 oil before putting the boat in the water this June. Yesterday, after ~20hrs of use, I pulled the dipstick to check the oil level and was greeted by very ugly dark oil. I know that not a lot can be read into what oil looks like on a dipstick or rag but I was expecting to see oil that still looked new.

Maybe the shop didn't change the oil?!?!?! Maybe this is normal behaviour for this engine and/or this type of oil? The engine did spend a lot of time idling during the ~20hrs of run time while teaching people how to surf/ride.

Thoughts ?
 
Hard to tell without a picture or knowing the history of the engine or how it was serviced.
 
ringmaster said:
2007 MasterCraft boat with GM Vortec Indmar 8.1L L18 running Valvoline VR1 Racing SAE 40 High Performance High Zinc oil.

I paid a shop to do a seasonal oil change with the VR1 oil before putting the boat in the water this June. Yesterday, after ~20hrs of use, I pulled the dipstick to check the oil level and was greeted by very ugly dark oil. I know that not a lot can be read into what oil looks like on a dipstick or rag but I was expecting to see oil that still looked new.

Maybe the shop didn't change the oil?!?!?! Maybe this is normal behaviour for this engine and/or this type of oil? The engine did spend a lot of time idling during the ~20hrs of run time while teaching people how to surf/ride.

Thoughts ?
Click to expand...
I think you need to be using a Marine Oil and not a Racing Oil. Contact Pablo here, he is an Amsoil Dealer, he could recommend an oil for you.

I could be wrong, but I do not think if someone is using a Racing Oil that the Motor should not be idled a lot. There are also some different characteristics between Racing Oil and Marine Oil.
 
Brian123 said:
I think you need to be using a Marine Oil and not a Racing Oil. Contact Pablo here, he is an Amsoil Dealer, he could recommend an oil for you.

I could be wrong, but I do not think if someone is using a Racing Oil that the Motor should not be idled a lot. There are also some different characteristics between Racing Oil and Marine Oil.
Click to expand...

it's an 8.5 tbn oil, with more friction modifiers and more phosphorous, and no VII. Not a marine oil, but it can be used for a normal oci.
 
The only time I get really blacked out oil by 20hrs is on 2 stroke Detroit diesels, gm 6.2 and 6.5l diesels, push lawnmowers and the push mowers aren't totally blacked out unless that engine is destroying it's self.
 
i would change with a fresh HDEO 5w-40. Chevron Delo 400 XSP, Mobil Delvac extreme etc. with a constant load like a boat engine sees and no emission issues, it’s a no brainer to step up to HDEO
 
demarpaint said:
Hard to tell without a picture or knowing the history of the engine or how it was serviced.
Click to expand...

300hrs on the engine and in excellent condition. Runs perfectly.
Jetronic said:
it's an 8.5 tbn oil, with more friction modifiers and more phosphorous, and no VII. Not a marine oil, but it can be used for a normal oci.
Click to expand...

I have a thread here from last year asking which oil to use in this engine. The VR1 seemed like a good answer - maybe not?
wpod said:
What did the oil look like when you first put the boat in the water?
Click to expand...

Unfortunately I didn't look at the dipstick before today. Amateur mistake!
BrendanC said:
i would change with a fresh HDEO 5w-40. Chevron Delo 400 XSP, Mobil Delvac extreme etc. with a constant load like a boat engine sees and no emission issues, it’s a no brainer to step up to HDEO
Click to expand...

The owner's manual states that 40wt oil is to be used in this engine. I had considered using Redline 20W-50 or Mobil 1 15W50 but IIRC the consensus was to stick with straight weight oil. The boat is only used in temps between 65F - 100F and the engine is always at full operating temp before going past 2500rpm so multi-vis doesn't seem very advantageous.
 
Oil color means nothing. My Jeep can turn oil dark very quickly. Always has. Meanwhile I have a few diesel machines that can look relatively amber colored after a season of use.

This engine likely saw many WOT runs. The oil is doing its job. There’s nothing wrong with your oil choice. Many people use a 15w40. I would switch to that only for cost reasons. Change it at the end of the season yourself and sleep well.
 
One thing to keep in mind is boats and PWCs suffer from a ton of fuel dilution. I’m no expert, but it seems reasonable to me that the fuel dilution could have changed the color that fast.
 
ringmaster said:
300hrs on the engine and in excellent condition. Runs perfectly.


I have a thread here from last year asking which oil to use in this engine. The VR1 seemed like a good answer - maybe not?


Unfortunately I didn't look at the dipstick before today. Amateur mistake!


The owner's manual states that 40wt oil is to be used in this engine. I had considered using Redline 20W-50 or Mobil 1 15W50 but IIRC the consensus was to stick with straight weight oil. The boat is only used in temps between 65F - 100F and the engine is always at full operating temp before going past 2500rpm so multi-vis doesn't seem very advantageous.
Click to expand...
How hot does the oil get?
 
@ringmaster
Sorry, hate to say it but I am the skeptic so I will say it. HIGHLY SUSPICIOUS that oil was changed. No way should it be black. Anyway, only way to know is change it and see another 20 hours.
Sad but true, it happens I am sure often. Trust no one and always look after a change

BTW- Your oil choice is a good one
 
My 06 Mercury 496HO 8.1 would turn the oil black at same hour interval. Stock it was fine. I had Whipple Superchargers stage 2 tune uploaded on the stock pcm. It adjusts air/fuel ratio and bumps timing. It ran very rich. Oil smelled of fuel and would turn black in 20ish hours. Mobil Delvac 15W40 oil.

20171112_153254.webp


20171112_142455.webp
 
You must log in or register to reply here.

Similar threads

R
Vortec Indmar 8.1L (boat) oil suggestions? 40WT
Replies
18
Views
4K
OVERKILL
Redhawk454
After 1,800 miles my motor oil is black (gasoline engine)
2
Replies
22
Views
4K
DHBWA
T
  • Question Question
Advice on OCI in dusty conditions low mile use
2
Replies
27
Views
2K
oil pan 4
scubapr
Toyota / Lexus A25A-FXS Hybrid engine oil questions
2
Replies
33
Views
4K
The Critic
A
Help with Engine knock - rod bearing/hydaulic lifter/fuel injector, which one?
2
Replies
28
Views
2K
kschachn
Back
Top