# What do I need to know about owning a Mercury Pro XS?



## goodwood (Mar 30, 2009)

out of warranty
would like to DIY some maintenance if possible
400-600 hrs


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## FishAfrica (Jan 23, 2010)

The following is from a Basser forum, this guy really knows his stuff on Mercurys:

_This list will be updated as additional information is requested- check it regularly for the most current information!

_*Oil:*
-These are the "top recommendations". _Refer to your owner's manual for other oil specifications!_
-ALL EFI/CARB 3.0L Engines: Mercury or Quicksilver Premium *PLUS*
-All STANDARD Optimax (75-250): Mercury or Quicksilver DFI/Optimax Oil
-ALL ProXS Models: *Optimax/DFI Oil*. Mercury or Quicksilver Premium *PLUS* is acceptable, but Optimax/DFI oil is RECOMMENDED due to a better additive package to help combat carbon deposits.
-ALL Racing/XS Models: PREMIUM PLUS

- (Note..... there was some conflicting information on Merc's Website- follow this recommendation for the latest information as it's released!)

*Battery:* 
-MINIMUM 800CCA or 1000 MCA Capacity. More is better! Use Stainless Steel Lock nuts (don't use wing-nuts).
-IF you have a lot of accessories you are running, KEEP IN MIND that this specification is for the ENGINE CRANKING BATTERY. You may need to INCREASE the battery specification to provide adequate cranking capacity based on your accessories being run! 
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(Recommended Batteries after Testing and information courtesy of Mercury Marine Research & Development)

-Odyssey PC1500, PC1700, PC2150 and PC2250.
-Optima Group 31
-West Marine Sea Volt Group 27 AGM.
-Cabela's Advanced Angler ** Group 24 and 27.
-Trolling Thunder TT1175 and TT1370.
-Excide Megacycle (Mercury Brand) MC-31 and XMC-31.
-Sears Die Hard Platinum 34M and 31M.
-Deka Sea Mate 8A27M and 8A31DTM.

** During initial testing, these batteries do not meet their advertised cranking ratings.
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*Spark Plugs:* 
-QL77CC (Champion) for 3 Liter EFI's (.035" 2001 and prior and ALL 250XB, .040" 2002-up)
[email protected] .032-.033" for Standard Opti's 135-225HP and 200 ProXS PRIOR TO Serial Number#1B912786
-IZFR5J @.032-.033 for 75-115 Opti's
-IZFR6J for 150, 175, 200 ProXS (Serial #1B912786-up) & 225-250 ProXS and Racing XS Motors 
-2005 & prior: .032-.033"
-2006 & up: .042-.044" gap for best idle performance. (150/175/225/250 ProXS/XS)
_- *250 XS/ProXS* can use *IZFR6J* (gapped to .042-.044") OR *IZFR6J-11* (pre-gapped, currently a "factory only" plug)_
-2006 & up 225 ProXS: .042-.044" 
-175 ProXS: .042-.044"
**** 200 ProXS Models manufactured PRIOR TO 2/1/12 utilize IZFR5G Plugs.
*** 200 ProXS Models manufactured AFTER 2/1/12 (Serial Number 1B912786 and later) will utilize IZFR6J (gapped at .042-.044") due to production changes in the engines.*

-IZFR7M for 300XS: .044" Gap

*FUEL:*
-All models- MAXIMUM ETHANOL CONTENT: 10%. Ethanol content may adversly affect engine performance. 
-See "Mercury's View of Ethanol" on Sherm's board at: Mercurys take on Ethanol blended fuel
-Standard Opti's (ALL) 87 Octane MINIMUM. 
-XS, XB or Racing PRIOR to 2006- CONSULT OWNER'S MANUAL! Most require High-Test!
-ProXS and 250XS 2006-later: 87 Octane MINIMUM. Idle quality may improve with 89 Octane (mid-grade).
-300XS- Consult Owner's Manual. High Grade (minimum 91 Octane) fuel required!

*Fuel Additive Recommendations:*
-Stabilize fuel ANYTIME fuel will not be consumed and replaced within 15 days!!!
-Optis (ALL, including XS & ProXS): *Quickleen in EVERY TANK OF FUEL.* You CAN combine Mercury QuickCare or QuickStor Fuel System Treatment & Stabilizer (or Sea-Foam if you prefer it) with Quickleen. Use the recommended "dose" of each product per the bottle instructions. For anyone questioning Quickleen recommendation- see Service Bulletin 2001-12 (yes, it's been recommended since 2001!!!).
-Quickleen may be used in ANY Mercury engine- it helps to prevent/remove carbon buildup (primary purpose).

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*"Mercury Component Cocktail"* (Chemically, this works much the same as the previously recommended (and now to avoid alcohol content) cocktail, and requires less components.) This is _*Don's Preferred "Cocktail"*_:

-1oz Mercury QuickCare per 5 gallons fuel
-1oz Mercury QuickLeen per 5 gallons fuel
(If leaving fuel in boat for more than 30 days, be sure to also add Mercury QuickStor).
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*Fuel/Air Pressures (Optimax):*
Two different pressure differentials are used:
-75-115 3 cyl. and ALL XS Racing & 225-250 ProXS Motors (And the 250 Optimax) use 94/108 Air/Fuel Pressures (Fuel pressure equals air pressure + 15psi) 
-All other "standard" Opti's use 80/90 Air/Fuel Pressures (Fuel pressure equals air pressure + 10psi)
-IF YOU HAVE NO AIR PRESSURE- YOU HAVE LITTLE OR NO FUEL PRESSURE. The fuel pressure is DIRECTLY relative to the AIR PRESSURE! So- if you have low or no fuel pressure, CHECK the air pressure, and check for AIR LEAKS before you start replacing fuel pumps!









*** Neat little "rule of thumb": If it has "gray" Direct injectors, Air/Fuel is 94/108 and it uses a spark plug that 'ends in J or M' *** (one motor exception- it had black injectors with a "white dot"- consider those to be "gray").

If the direct injectors are Black, Black with a Blue Dot, or Blue, the Air/Fuel is 80/90 and the spark plug probably ends with a "G".


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## FishAfrica (Jan 23, 2010)

And heres some more helpful info on Mercs: http://www.bbcboards.net/mercury-3-...d-posts-look-here-first-updated-2-2013-a.html


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## PENSTX (Jul 18, 2011)

All you need to know is that you will get crazy good fuel mileage and tons of power!


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## FishAfrica (Jan 23, 2010)

Also learned in my research that a lot of the power head failures in Mercs are caused by "cold seize" in the number 6 cylinder. When its cold let her warm up for several mins, and cool her down after a long hard run by letting the motor run to dissipate the heat.


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## RedXCross (Aug 7, 2005)

120 degrees on my Merc monitor before takeoff.it is a must I know a bunch who don't. T stats and computer


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## target (Feb 12, 2013)

Use only DFI/Opti oil.
Merc changed the reccomendations to exclude Premium Plus / TCW3 oil on all Optimax and Pro XS motors ( unless you're out and that's all that's available. Go back to DFI oil as soon as possible).

I believe that this has to do with the occurance of sooting with alot of idling as done with fishing.
The Pro XS motors originally reccomended Premium Plus oil but were usually run on "Go Fast" boats that did not idle for long periods. Now most bass boat come equiped with Pros and half of their run time is below 2000 rpms.

With spark plugs costing $20ish+ ea, I'd want them to last as long as possible.

From the Mercury service manual:

*Every 100 Hours of Use or Once Yearly, Whichever Occurs First​*1. Lubricate all lubrication points. Lubricate more frequently when used in salt water.
2. Inspect and clean spark plugs.
3. Replace water separating fuel filter.
4. Replace compressor air intake filter.
5. Check corrosion control anodes. Check more frequently when used in salt water.
6. Drain and replace gearcase lubricant.
7. Lubricate splines on the drive shaft and shift shaft.​​​​*​
8. Check power trim fluid.
9. Inspect battery.
10. Check control cable adjustments.​​​​*​
11. Check tightness of bolts, nuts, and other fasteners.​*Every 300 Hours of Use or Every Three Years, Whichever Occurs First​*1. Replace water pump impeller (more often if overheating occurs or reduced water
pressure is noted).​​​​*​
2. Replace the alternator and air compressor drive belts.​3. Replace the two in-line oil filters in the air compressor oil return lines


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