g2020
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Here are three jobs that are or were part of my monthly maintenance routine. I learned about these after I joined this forum. In addition to keeping parts or systems in good working order, these jobs involve lifting the hood and crawling under the vehicle every month. Needless to say, this can lead to early detection of a problem before the problem triggers a warning indicator on the dashboard.
- If you ever see an oil stripe in the engine canyon (and on the hood liner) of your vehicle, check out how to repair the alternator/generator decoupler pulley, as first described by @darkhorse13. In my case, I had the alternator replaced with a reman and repaired the original to serve as a spare. Also, have your vehicle inspected by a professional.
In my opinion, it makes sense to replace the PSF in the power steering fluid reservoir for as long a vehicle is driven regularly. Replacing the fluid in the reservoir, with the correct MOPAR power steering fluid, costs about $7.00 per job. Partial replacement of the ATF in the transmission also provides value, but only for 11 or 12 months. After that, the amount of old ATF replaced each month is so small that it makes financial sense, at about $52 per job, to stop until after the next pan drop is completed. As for draining the radiator each month, I removed this maintenance from my monthly routine because, at $28 per job, I learned the hard way that it can be all for naught when an unrelated repair also involves replacing some or all of the coolant.
But wait, there's more.... At $6.00 per job, it can make sense to replace the coolant in the coolant reservoir for as long a vehicle is driven regularly. The concept is exactly the same as that of reservoir-only PSF replacement, and the investment in coolant is up to 80% lower than that of the radiator drain method. See Section 3B below.
- This post is a bit heavy on the math, but it is the math that justifies engaging in (or not) each of these maintenance practices.
- In order for any of these maintenance practices to be effective, the vehicle must be driven regularly / several times per week.
1. Power Steering - Reservoir-Only PSF Replacement - Turkey Baster Method
Note: This section has been revised to include an overfill of 0.5 liters (0.53 quarts, simplified to 0.5 quarts) as shown in the ZF instructions (see first attachment in Pan Drop Instructions).
>>> REQUIRED: Do not skip "driving the vehicle" or ATF LEVEL CHECK.
This method should only be used after a pan drop, or transmission drain & fill (NEVER a flush), has been performed to remove contaminants from, and replace the filter in, the transmission.
Note: Draining the radiator is no longer part of my monthly maintenance routine
- Also see Section 3B below
Another way to replace the coolant over time:
References
People:
Websites:
Related Posts
- If you ever see an oil stripe in the engine canyon (and on the hood liner) of your vehicle, check out how to repair the alternator/generator decoupler pulley, as first described by @darkhorse13. In my case, I had the alternator replaced with a reman and repaired the original to serve as a spare. Also, have your vehicle inspected by a professional.
In my opinion, it makes sense to replace the PSF in the power steering fluid reservoir for as long a vehicle is driven regularly. Replacing the fluid in the reservoir, with the correct MOPAR power steering fluid, costs about $7.00 per job. Partial replacement of the ATF in the transmission also provides value, but only for 11 or 12 months. After that, the amount of old ATF replaced each month is so small that it makes financial sense, at about $52 per job, to stop until after the next pan drop is completed. As for draining the radiator each month, I removed this maintenance from my monthly routine because, at $28 per job, I learned the hard way that it can be all for naught when an unrelated repair also involves replacing some or all of the coolant.
But wait, there's more.... At $6.00 per job, it can make sense to replace the coolant in the coolant reservoir for as long a vehicle is driven regularly. The concept is exactly the same as that of reservoir-only PSF replacement, and the investment in coolant is up to 80% lower than that of the radiator drain method. See Section 3B below.
- This post is a bit heavy on the math, but it is the math that justifies engaging in (or not) each of these maintenance practices.
- In order for any of these maintenance practices to be effective, the vehicle must be driven regularly / several times per week.
- In every case, the fluid needs to be cycled through the system many times, at normal operating temperature, before starting the next job
- Always check the level again the next day.1. Power Steering - Reservoir-Only PSF Replacement - Turkey Baster Method
- This method should only be used after a power steering flush has been performed to remove debris from the power steering system.
- The turkey baster method has a single-job replacement rate of 13% (3.648 fl oz replaced, divided by 28 fl oz estimated total capacity). Eighty-one percent (81%) of the original fluid is replaced after 12 jobs, and 91% is replaced after 17 jobs. The source of estimated total capacity is a video in which the presenter measured everything as he completed a power steering flush, but I don't have the link.
- Refill the reservoir to the midpoint between MIN and MAX when the engine is COLD, and do NOT overfill.
- Curious about 99% replacement? It requires 33 jobs.
- Calculation: 1-(1-3.648/28)^33 (this calc can be dropped into Google search) = 99%
- After just 13 months of replacing the PSF in the reservoir each month, the PSF in a Gladiator that previously had not been flushed for three years will have an average age of one year old. After 33 jobs, the average age of the PSF is seven months old. Using only this method, the average age bottoms out at, or will never be less than, 6.67 months old.
- Cost per job = $6.28 (3.648 fl oz), and cost per year = $76 (2.74 pints)
- In my opinion, PSF in the reservoir should be replaced each month for as long as the vehicle is driven regularly
- @Hootbro told us about the turkey baster method (super easy)
Note: This section has been revised to include an overfill of 0.5 liters (0.53 quarts, simplified to 0.5 quarts) as shown in the ZF instructions (see first attachment in Pan Drop Instructions).
>>> REQUIRED: Do not skip "driving the vehicle" or ATF LEVEL CHECK.
This method should only be used after a pan drop, or transmission drain & fill (NEVER a flush), has been performed to remove contaminants from, and replace the filter in, the transmission.
- The no-drop method, with 0.5-Liter Overfill & Driving the Vehicle as recommended in the ZF instructions, has a single-job replacement rate of 20% (see "No-Drop Replacement Rates" in Section 15 of Pan Drop Instructions). Eighty-three percent (83%) of the original fluid is replaced after 8 jobs, and 93% is replaced after 12 jobs.
- Calculation: 1-(1-(1.5+0.5)/(9.5+0.5))^12 = 93%, where 0.5 = overfill
- Removing (and replacing) just one additional cup (8 fl oz) of ATF from below the fill plug, using a 200 cc syringe, results in 92% replaced after 10 jobs. Removing two extra cups gets to 92% after 9 jobs. Removing more is better, but the extraction tube should NOT be forced when it meets resistance below the fill hole.
- In my opinion, achieving more than 93% fluid replacement after 12 jobs, using this method, is not worth the cost. After 12 jobs, less than 1.5% of the original fluid is replaced per job.
- Cost per job = $52 (2 quarts, including 0.5-liter overfill), and cost per series of 12 jobs = $611 (24 quarts)
- Results for one less job: 91% is replaced after 11 jobs, and cost per series of 11 jobs = $560
- Calculation: 1-(1-(1.5+0.5)/(9.5+0.5))^11 = 91%, where 0.5 = overfill
- By comparison, a series of three pan drops (91% replaced) costs $487, and a series of four pan drops (96% replaced) costs $640 (including one gasket and accounting for fluid remaining in pump).
- Results for one less job: 91% is replaced after 11 jobs, and cost per series of 11 jobs = $560
Replacement Rates
- This is a partial list of the most informative results
- A more complete list of replacement rates with 0.5-Liter Overfill & Driving the Vehicle is shown under "No-Drop" Replacement Rates in Section 15 of Pan Drop Instructions
1 job: 20% of original fluid replaced
4 jobs: 59% of original fluid replaced, <10% replaced per job after 4 jobs
8 jobs: 83% of original fluid replaced, >80% replaced after 8 jobs
11 jobs: 91% of original fluid replaced, >90% replaced after 11 jobs, <2% replaced per job after 11 jobs
12 jobs: 93% of original fluid replaced, <1.5% replaced per job after 12 jobs
14 jobs: 96% of original fluid replaced, >95% replaced after 14 jobs, <1% replaced per job after 14 jobs
21 jobs: 99% of original fluid replaced
- Some old ATF will always remain after a pan drop or no-drop. Monthly replacement, of old ATF from above the fill plug, increases the concentration of new ATF (and new additives) in the transmission and, ultimately, prevents or reduces oxidation. Unlike a pan drop, however, a no-drop does not involve replacing the filter or cleaning the magnets.
- A more detailed explanation of the reason for monthly fluid replacement, using the automatic transmission as an example, is provided in post #5 in this thread.
- For a brief description of a no-drop, see Section 14 in Pan Drop Instructions. A 200 cc syringe, a 1.5-liter syringe (and ATF108 adapter), or a 2-gallon fill pump (and ATF108 adapter) may be used to dispense/fill 2.0 quarts of ATF (including 0.5L overfill), which should net 1.5 quarts after the ATF level check is complete (and if the ATF level was correct before starting the job). Do not skip "driving the vehicle" or ATF LEVEL CHECK.
- Some other tools are required for a no-drop, but not as many as those that are required for a pan drop.
- A (full) pan drop must still be performed according to the pan drop service interval (see ATF for Automatic Transmission, under Important Reminders).
- @Maximus Gladius taught me how to do a pan drop
Note: Draining the radiator is no longer part of my monthly maintenance routine
- Also see Section 3B below
- This method should only be used after a cooling system flush has been performed to remove debris from the cooling system.
- The radiator drain method has a single-job replacement rate of 38% (1.25 gallons replaced, divided by 3.25-gallon cooling system capacity for the 3.6L gasoline engine).
- In my opinion, achieving more than 98% fluid replaced after 8 jobs, using this method, is not worth the cost. After 8 jobs, less than 1% of the original fluid is replaced per job.
- Calculation: 1-(1-1.25/3.25)^8 (this calc can be dropped into Google search) = 98%
- Cost per job = $28 (1.25 gallons), and cost per series of 8 jobs = $217 (10 gallons)
Replacement Rates
1 job: Total of 38% (1.25 gallons) of original fluid replaced
3 jobs: Total of 77% of original fluid replaced, <10% replaced per job after 3 jobs
5 jobs: Total of 91% of original fluid replaced, >90% replaced after 5 jobs
8 jobs: Total of 98% of original fluid replaced, <1% replaced per job after 8 jobs
10 jobs: Total of 99% of original fluid replaced
- Some repairs can defeat the purpose of cycling in fresh coolant each month, such as fixing a leaky oil cooler, replacing a thermostat, or replacing a water pump. If much or all of the coolant is replaced as part of a repair, the coolant pH will be optimal once again and the coolant additive clock will be reset. For this reason, draining the radiator is no longer part of my monthly maintenance routine. Unless a vehicle is used for severe duty such as off-roading or trailer-towing, the coolant should be good for five years with annual/seasonal inspections.
- A pH test can help you determine whether the coolant needs to be replaced. Recommended pH is 8.5 +/- 1.0 (low-to-mild alkaline/basic). The coolant should not be acidic (pH below 7.0).
- It should be noted that draining the coolant by disconnecting the radiator hose is much safer and slightly faster, but using the radiator drain method is 1) very clean and 2) workable for someone who lives in a place where auto maintenance is banned.
- @biodiesel introduced us to the Thexton socket, which is, in my opinion, the key to using the plastic radiator drain WITHOUT breaking it
Another way to replace the coolant over time:
Note: For severe-duty, including off-road use and trailer towing, there is no substitute for doing a cooling system flush to remove debris from the cooling system. In general, the service interval for severe-duty is about 40% to 50% of the service interval for normal driving. However, a pH test can help you determine whether the coolant needs to be replaced. Recommended pH is 8.5 +/- 1.0 (low-to-mild alkaline/basic). The coolant should not be acidic (pH below 7.0).
With that said, I have started to replace the coolant in the reservoir (coolant recovery bottle) each month because the technique is very simple, has almost no risk of damage or spill, and costs only $5.41 (1 quart) per job. About 23% more coolant, than that of the radiator drain method, is required to achieve 98% replacement. Achieving 98% replacement requires 49 jobs. Calculation: (1-(1-0.25/3.25)^49). To achieve 99% replacement, 58 jobs are required.
This method should only be used after a cooling system flush has been performed to remove debris from the cooling system.
I ran across a post about reservoir-only coolant replacement on Reddit in 2025. I discounted it at the time, but then reconsidered because the replacement rate of the original fluid is even lower than that of the turkey baster method for PSF. In this case, slower is better because, as explained in the next paragraph, it significantly lowers financial risk resulting from an unrelated repair.
The monthly cost of the radiator drain method ($28 per month, 8 monthly jobs to achieve 98% replacement) is too high to make financial sense if an unrelated repair occurs and it involves replacing some or all of the coolant. With reservoir-only coolant replacement, or the syringe method ($5.41 per month, 49 monthly jobs to achieve 98% replacement), the coolant replacement rate is 84% slower (1-8/49) to achieve 98% replacement, and the investment in coolant is up to 80% lower (calculation: 1-($5.41*8)/$217, at the eight-month mark).
Using this method, the old coolant is completely replaced about every five years. After five years of monthly reservoir-only coolant replacement, the average age of the coolant will be about 14 months old. The average age of the coolant bottoms out at, or will never be less than, one year old. The five-year coolant cost is $325 (60 quarts, or 15 gallons).
In terms of visible results, the inside of the coolant reservoir will remain clean. A clean coolant reservoir does not necessarily mean that there is no debris in the cooling system. However, it does mean that the usual coolant mineral buildup that slowly forms in the coolant reservoir, over time, will be greatly reduced as long as the coolant in the reservoir is replaced each month.
Of course, there is the option to do a cooling system flush every five years. I prefer, however, to reach the point at which the average age of the coolant in my Gladiator is consistently between 12 and 14 months old.
Will a cooling system flush be required if the coolant in the reservoir is replaced each month? If you frequently go off-road or tow a trailer, the answer is "Yes". Some folks who regularly go off-road and tow a trailer change the coolant annually or every 30,000 miles, but a pH test may indicate that this is excessive. If you use your vehicle as a daily driver (on-road), never drive aggressively, and rarely get stuck in traffic, the service interval can be much longer. Testing the pH every couple of years, and tracking the results, can help you determine when the coolant needs to be replaced. The warranties for XEREX G30 (5 years / 150K mi), MOPAR (10 years / 150K mi), and PEAK Purple (15 years / 350K mi) are not helpful because the warranty period range is so wide. (Each of these coolant products is OAT-formulated and MS.90032 & MS-12106 compliant.) Even if you drive conservatively and replace the coolant in the reservoir each month, without fail, I recommend doing a cooling system flush every ten (10) years or sooner. A pH test is an excellent tool, but it does not measure the amount of debris in the cooling system. As a reminder, the syringe method should only be used after a cooling system flush has been performed.
For this job, I recommend using a 200 cc automotive syringe, such as SEDY 88082, instead of a turkey baster because using a syringe is faster and there is less dripping.
In my opinion, it is not a bad idea to replace the coolant in the reservoir each month for as long as the vehicle is driven regularly. If a repair of a different part happens to require that the coolant be replaced, so be it. The investment in replacing the coolant each month will be lost, but the coolant additives and pH will have been refreshed along the way.
References
People:
@biodiesel (Thexton socket, in Section 3)
@darkhorse13 (how to repair alternator/generator decoupler pulley, in the first paragraph)
@Hootbro (turkey baster method, in Secton 1)
@Maximus Gladius (pan drop, in Section 2)
Websites:
https://www.jeepgladiatorforum.com/forum/threads/alternator-pulley-leaking.62812/page-3#post-1664611
https://www.jeepgladiatorforum.com/forum/threads/alternator-pulley-leaking.62812/page-4#post-1666481
Related Posts
General
This post is a collection of links to my articles on fluids & filters for a Jeep Gladiator
Power Steering
This post is a review of several OEM and aftermarket PSF options, with links to prices, price indexes (per single job and per fl oz, as of January 2025), equivalence rating, and other key details.
Automatic Transmission
This is a set of written instructions on how to do a pan drop on a Jeep Gladiator or Wrangler 2018+. Reference docs and photos are also included.
- These instructions also apply to the ZF 8HP75 installed on models equipped with the EcoDiesel 3.0L V6 engine
- This post includes documentation of the correct ATF for the automatic transmission, service intervals, and more.
Radiator
This post is a review of PEAK antifreeze + coolant and competing brands. Emphasis is placed on specific equivalence to the OEM original, warranty terms, and key details from the label.
Other Maintenance
This post advises what you need, including verified tool sizes and torque specifications, for the subject jobs.
Note: Removing the differential cover to inspect and clean the differential and axle tube is out of scope
- This post also includes references to six additional individual jobs
Sponsored
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