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'06 Off Road
60 Posts
2006 Off Road, ~178 km (originally sold in Canada), CaptainInsane-O, Transmission rebuilt and Aluminum 3-row radiator ordered

Bought the Xterra end of October, 2020. Was aware of SMOD being a problem with these things, so I checked the trans fluid and radiator for any signs of a leak (both were OK) and verified that the radiator bypass had been done, before I closed the deal. Roughly four months / 1100 km later the trans suddenly started slipping and whining like a worn out 6/71. Dropped the pan... the fluid looked worn (more brown than red) and there was a good bit of clutch pack sludge built up in the bottom of the pan, but still no signs of SMOD. I cleaned the pan, reinstalled it and flushed roughly 4.5 gallons of new trans fluid through the system. This seemed to do the trick, but unfortunately only lasted for about one month / 500 km. Dropped the pan again and fluid was pretty saturated with dissolved clutch material. I went ahead and dropped the valve body this time and found evidence of a prior SMOD event in the form of very thick, milkshake globbed within it. At this point I threw in the towel and tagged in my transmission guy. He concurred with my SMOD in the past diagnosis & said that the coolant contamination contributed to accelerated breakdown of the clutch pack materials and subsequent tranny implosion.

The Cuu-koo Capt'n

11 Posts
Apologies if this or something similar is posted elsewhere. I tried searching for a poll, but I did read through some of the extensive threads and captured usernames, years, mileage and outcome. If you are finding this from other sites, this is an issue that, in addition to Xterras, affects Pathfinders and Frontiers. Where the radiator fails and coolant mixes with automatic transmission fluid. THIS DOES NOT AFFECT MANUAL TRANSMISSION MODELS.

What is SMOD?
= Strawberry Milkshake Of Death (basically what your transmission fluid looks like after mixing with coolant.) The coolant and transmission fluid mix due to an internal failure in older model Nissan radiators.

Here's a Good Description on SMOD Causes, by Forum Member Robert Bills:

How can I tell if I have SMOD?
Symptoms include: Strawberry Milkshake like sludge on underside of radiator cap. (Check when engine is cool.)
  • Rumbling / shaking around 50+ from the transmission (feels like you are driving over rumble strips)
  • General transmission issues (slipping, poor shifting, hard shifting, etc)

What can I do to prevent SMOD? / What is ByPassing?
You could upgrade to the new Nissan radiator (part # needed) or put in an aftermarket radiator.

Alternatively, you could potentially 'ByPass'. ByPass = Re-routing cooling lines so the transmission does not utilize the radiator for additional cooling. Members have mixed views on this. Some say its fine, others feel that it reduces cooling capacity, especially in Xterras that are off-roaded or tow. "ByPassing" is a preventative measure. Once damage has been done its either new parts or possibly a flush.

Nissan also has an extended warranty in place (see below).

Additional information on by-passing:

What can I do if I have SMOD?
First, if you do or suspect you have SMOD - stop driving the Xterra as soon as possible to limit further transmission damage.

Next, most people end up with a New / rebuild of Transmission and new radiator system + updated fluid and removal of all contaminated fluid. Typically Nissan does cover this.

Alternatively you could try flushing the system and just changing the radiator. Some members have reported they have "saved" the transmission that way. Depends on how long you have been driving with this issue and the level of damage done to the transmission.

Other general information:
  • Nissan has issued an extended Warranty that covers transmission failures related to the flawed radiator design. Covers 2005-2010, 100% till 80,000 - over 80k deductibles are required.
  • Link to extended warranty: Home - Nissan Assist
  • So far there have been no failures from 2009 on wards (and the 1 2008 listed is likely a false positive).

Disclaimer, (in other words, before you freak out): The data reflected in this post, and on this board is of a small subset of total Xterras on the road and sold. Overall, the Xterra is a reliable truck. Most users who find this post are here because they have SMOD, few people sign on to say "everything has been great". You'll also note that the data so far reflects early year Xterra's (2005, 06 & 07). These are also the years with the most Xterra's sold and those that have the most miles on them. However, these are also the years with the old coolant type and radiator design.

Saved = Typically new radiator, hoses, and multiple flushes with Matic-S
New Transmission: Exactly that. Some covered, some weren't.

I plan to make this list eventually more sort-able and capture counts. But for now here it is.

Additionally I'd love to get data points for those that have by-passed how long they have been running it, whether or not they have an aux cooler, and if they have had any issues (overheats or still SMOD).

Lastly, I'm trying to find out what year the switch from Matic-J to S occurred (updated: 2009 = fluid switch) and when (if at all) a new radiator part was issued. <-- General concensus is that a new radiator has been implemented. Exact date unclear (either in MY 2009, 2010, or 2011).


SMOD List (updated 10/30/2015)

• 56,000 – mac_man2507 (new transmission)
• 120,000 – 6pack (saved)
• Texterra (saved)
• 65,000 – synjohn
• 115,000 – GhostX (saved )
• 103,000 – TRON (saved)
• 79,000 Riehle (unknown)
• Draines (unknown – frontier)
• 100,500 – tsiturbomightym (new transmission)
• 92,000 – zambonikane (new transmission)
• 56,000 – alexterra (new transmission)
• 80,000 – rockdog (new transmission)
• 84,000 – micheljm (new transmission)
• 90,000 – Hinsx (new transmission)
• 103,000 – guedesigns (unknown)
• 82,000 – jaysonics (upgraded to 2011 Xterra)
• 72,000 – KpnObvious (new transmission)
• 110,000 – Blucas (new transmission)
• Machine>Matter (new transmission)
• 39,000 nporecords (new transmission)
• Nexus_7
• Peasy207
• First class X (new transmission)
• 40,000km vandman
• 130,000k - mango (saved)
• 78,000 - pkiddddd (new transmission)
• 77,000 - Dirtbag (new transmission)
• 137,000 - Salsa E 2005 Pathfinder (saved)
• 80,000 - Texterra (saved - 2 flushes and new radiator) - Now at over 316,000+ miles w/out issues!
• 105,000 - skipper172
• 175,000 - gorillamel (Saved: by-passed, but had overheat issues and by-pass removed. Got SMOD sometime after.)
• 115,000 - mtbx (new transmission)
• 117,000 - EsotericSYN (saved)
• 114,000 - chicago111 (saved)
• 120,000 - mmkco (saved?)
• 123,391 - Strat1tude (saved)
• 59,778 - jeffnjm3 (new transmission)
• 127,000 - drink
• 330(km) - Scoop
• 120,000 - nixorz
• 69,000 - alex_godmar (saved)
• 93,000 - DucXterra (new rad and trans)
• 69,000 - Shagaroo (new rad and trans)
• 168,000 - raleighx (new rad and trans)

• My3rdx (saved)
• 98,000 p.staff
• 160,000 – paffcon (saved)
• 85,000 – klrkknt81 (new transmission)
• 06_xterra_s (saved)
• 50,000 - Xterra3100 (new transmission)
• 63,000 - az_jerry (new transmission)
• 69,000 - dutch169 (new transmission)
• 86,000 - Mnemonic (new transmission)
• 80,000 - Metal-X-Militia (new transmission)
• DaveGH
• 105,000 - oskon187
• 207,000 - Notread - (possibly saved?)
• 176,000 - DriverX
• 74,500 - dignow (new transmission)
• 81,000 - G&L (new transmission & new radiator)
• neflihim (saved)
• nolesfan (saved, then bought a 2013)
• 117,000 - socaloverlander (flushed / saved)

• 111,000 – White07x (new transmission)
• 63,000 xguy4life (saved)
• 84,000 camaro194 (new transmission)
• 65,000 miketerra07 (new transmission)
• Frasersxterra (saved)
• 75,500 - Chug
• 106,000 - Weber58 (new transmission)
• 79,300 - Evan77 (new transmission)
• 105,000 - JohnCB (new radiator + flush)
• 124,000 - Un4Seen (new radiator + flush)
• 137,000 - ThorX (New rad + flush, lasted for 1 year, needs rebuild or new trans)

• 158,000 - sullivan (new radiator, flushes, saved)
• 61,000 - Ramsker (new transmission & radiator - dealer covered)

• 100,013 - jimmpotter
• 75,000 - painroller (new radiator + trans)
•186,000 - (Flushed, cleaned radiator, by-passed trans oil to front oil cooler- saved)



ByPassed Trucks
- List members and mileage / time they have been bypassed

  • 2007 X - KillSwitch, bypassed for 30k miles, no SMOD or issues
  • 2005 X - Surf and Snow - bypassed for 3 years, no issues
  • 2007 X - rthinchey - Bypassed at 78k. now at 94k and no problems
  • 2005 X - Tib - Bypassed for over 3 years, over 40K miles since bypass, no aux cooler, no smod, no issues.
  • 2008 X - El'Zilcho - Bypassed for 5,000 miles, no issues
  • 2005 X - shralp313 - Bypassed @ 110k
  • 2010 X - g6620 - Bypassed @ 36k, plus external cooler
  • 2006 X - unamused - Bypassed @ 35k, now at 100k, no issues

Premium Member
2005 Lava Red X AT
2 Posts
Excellent post, I am so impressed with the organization, detail and breadth of extensive topics here! BTW, I am new to the community.

2005 X w/ AT
Currently treating SMOD
Bypassed w External Cooler @ 165K miles
Flushed both RAD and AT
New RAD, New RAD Hoses next step (175K miles)
No apparent issues, runs fine in all gears / all 4WD

Expecting better performance (power, mountain shifting) with these steps!

124 Posts
For what it's worth - and I should have contributed to this thread years ago:
2010 SE - bypassed at approx 70k? by dealer, currently 123k, no issues.

2,685 Posts
For what it's worth - and I should have contributed to this thread years ago:
2010 SE - bypassed at approx 70k? by dealer, currently 123k, no issues.
Thanks for posting. A lot of people here seem to think anything past 2008 is safe because there aren't many examples. I am happy for you that yours happened under warranty at least.

124 Posts
Thanks for posting. A lot of people here seem to think anything past 2008 is safe because there aren't many examples. I am happy for you that yours happened under warranty at least.
Yeah, the internet is weird place, creates not only a falsity of confidence, but a simultaneous sense of doom and gloom. In my case, the dealer suggested it before I even knew what SMOD was, and since I trust the dealer and there was no charge, I said "sure" - many years later I'm probably glad I did, one less thing to worry about.
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