General maintenence mileage vs hours
Mar 21, 2018 | 01:23 PM
#1
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General maintenence mileage vs hours
General maintenance schedule question here. Specific maintenence procedures are often instructed to be completed at either a specific mileage or time whichever comes first. For instance in my Haynes Tacoma repair manual it says to replace the spark plugs every 30,000 miles or 24 months whichever comes first. I get that when you don’t use a vehicle regularly it can be just as detrimental or even more so in certain circumstances to particular components than if the vehicle gets regular use, hence the “whichever comes first.” My question is if you use the vehicle regularly, but don’t put many miles on it, should you still base your maintenence schedule off the time if it comes up first? I drive my truck numerous times a week, but I don’t tend to go particularly far (10-20 miles per use usually). The truck isn’t sitting for long periods unused, it’s just not going very far. That will roughly mean that for the 30,000/24 month maintenence I would be hitting the mileage closer to 48 months. I’m not shy about doing maintenence and I certainly don’t want to neglect my truck, but I also don’t want to be tossing money and time at jobs that don’t need to be done. I could also see certain things being more important to do on a time schedule than others, such as fluid changes vs mechanical adjustments. Any suggestions or insight is welcome.
Oh and I don’t figure it matters but I have a 96 Tacoma v6 4x4
Oh and I don’t figure it matters but I have a 96 Tacoma v6 4x4
Last edited by 808rambler; Mar 21, 2018 at 01:52 PM.
Mar 21, 2018 | 01:51 PM
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From: Portland, Oregon, USA
Welcome to YotaTech!BIG EDIT: Co_94_PU is correct, it has been a looooooog day. I need more coffee!
Follow Toyota's maintenance schedule as stated.
A good portion of the listed maintenance items in my 1987 Owner's Manual says to inspect components at a given time or mileage rather than just replacement.
Since Toyota built the truck, it is best to follow their recommendations.
Last edited by old87yota; Mar 21, 2018 at 08:49 PM. Reason: Fixed BAD advice....
Mar 21, 2018 | 02:33 PM
#3
You should follow the schedule.. Regardless of time or mileage.
Remeber maintenance doesn't just mean "it is time to change __", there are inspections that need done for mechanical and electrical parts, fluids degrade and become contaminated over time in some cases even more so with inactivity (for example crank case oil, as the temperature fluctuates in the day and night the engine " breaths " which leads to condensation. If you aren't getting the engine hot enough for long enough, IE it sits long periods and never sees long highway travel, this isn't going to evaporate.)
Remeber maintenance doesn't just mean "it is time to change __", there are inspections that need done for mechanical and electrical parts, fluids degrade and become contaminated over time in some cases even more so with inactivity (for example crank case oil, as the temperature fluctuates in the day and night the engine " breaths " which leads to condensation. If you aren't getting the engine hot enough for long enough, IE it sits long periods and never sees long highway travel, this isn't going to evaporate.)
Mar 22, 2018 | 11:07 AM
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I hear ya, and that all makes sense, especially with the fluids. I suppose I’m still wondering though, with an item such as valve inspection and adjustment why time would be such an important factor. It seems that would be completely dependent on engine use rather than disuse. Especially if you were running it relatively frequently and it wasn’t ever truly sitting for long periods. At this point it’s all more academic than me trying to weasel out of working on my truck 
mainly cause I enjoy tinkering!
mainly cause I enjoy tinkering!
Mar 22, 2018 | 11:32 AM
#5
In the particular case of valves..
I'm going to make up the service schedule here cause I don't want to go look it up..
So say it's 35000mile/24month and in your case you wouldn't hit 35000 miles in 48 months because you only drive it once a week instead of daily.
If you are not driving often then the oil has more time to evacuate the valve surfaces, sure depending on the engine there might be puddles the cam dips into, but this results in "dry" start ups which can cause the surfaces to wear faster. As well if the surface goes dry it is exposed to the atmosphere, dry metal wet air a few days of sitting and bam you've got surface rust (remember we use iron and aluminium oxides to make sand paper!)
I'm going to make up the service schedule here cause I don't want to go look it up..
So say it's 35000mile/24month and in your case you wouldn't hit 35000 miles in 48 months because you only drive it once a week instead of daily.
If you are not driving often then the oil has more time to evacuate the valve surfaces, sure depending on the engine there might be puddles the cam dips into, but this results in "dry" start ups which can cause the surfaces to wear faster. As well if the surface goes dry it is exposed to the atmosphere, dry metal wet air a few days of sitting and bam you've got surface rust (remember we use iron and aluminium oxides to make sand paper!)
Mar 22, 2018 | 11:47 AM
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From: Portland, Oregon, USA
Can you post a picture of your maintenance schedule for future reference?
I think the reasoning behind maintenance items such as valve adjustments being on an time schedule is to check the health of the engine (or other components) regularly. The valves might not need adjustment but you might catch a problem while you are already there. That is why most of the maintenance items in my Owners Manual are "Inspection" based. In other words, "check this item for proper function, if not with in specification, replace".
This reduces the risk of unexpected breakdowns but also allows you to keep parts that are still in perfectly working order.
To be honest, very few people actually follow "do this at xx,xxx miles or xx months, which ever comes first", although that is the best practice. Most people do maintenance by miles only, choose to only do oil changes, or just wait for something to go wrong.
I think the reasoning behind maintenance items such as valve adjustments being on an time schedule is to check the health of the engine (or other components) regularly. The valves might not need adjustment but you might catch a problem while you are already there. That is why most of the maintenance items in my Owners Manual are "Inspection" based. In other words, "check this item for proper function, if not with in specification, replace".
This reduces the risk of unexpected breakdowns but also allows you to keep parts that are still in perfectly working order.
To be honest, very few people actually follow "do this at xx,xxx miles or xx months, which ever comes first", although that is the best practice. Most people do maintenance by miles only, choose to only do oil changes, or just wait for something to go wrong.
Mar 23, 2018 | 11:08 PM
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That’s great info, thanks for humoring me with the discussion. It makes sense that Toyota would recommend inspection/services at regular interavals for those reasons. I sort of figured they were shooting for a “you should at least look around in there occasionally instead of driving it into the dirt you idiot” kind of approach. So I plan on being cautious about pushing service intervals too far. As discussed earlier fluid changes and the like make sense to be done at a more timely interval than based on mileage alone. That being said I think for purely mechanical adjustments ill probably stick more towards the mileage recommendation, possibly erring a bit on the early side if it seems like it’s going to be much longer than the time reccomendation. I’m playing around under the hood (looking and listening) frequently enough to hopefully spot anything starting to go bad. In any case thanks again. The tinkering continues!
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