7 Best Oil for Cars over 100K Miles – Buyer’s Guide

Pissed off of visiting the garage daily? Need an ultimate solution to all these vehicle problems?

Surprisingly, the relief is in oil! Yes, compatible oil is a solution to 90% of all vehicle related troubles.

Now, the problem can arise in choosing one. So, I’m here with my guide to suggest to you some of the best oil for cars over 100K miles.

I’ll be sharing my experiences and answering some of the questions that may buzz around your mind.

Table of Contents

quick Compression

Products NameViscosityLiquid VolumeOil TypePrevents LeakCompatible With
Royal Purple Motor Oil5W-30160 Fluid OuncesSyntheticYesCars
Valvoline Motor Oil5W-205 QuartsSynthetic BlendYesCars
Castrol GTX Motor Oil5W-30160 Fluid OuncesSynthetic BlendYesCars
Castrol EDGE Motor Oil5W-30160 Fluid OuncesFull SyntheticYesCars
Pennzoil Motor Oil10-W40160 Fluid OuncesConventionalYesCars, Trucks, Vans, SUVs
Pennzoil Platinum Motor Oil5W-30160 Fluid OuncesFull SyntheticYesCars, Trucks, Vans, SUVs
Valvoline Hybrid Vehicle Motor Oil5W-306 QuartsFull SyntheticYesCars, Trucks, Vans, SUVs

In a rush! check out the hotlist below for the Best Motor Oils for High Mileage Engines (over 100k miles): (Affiliates links)

  1. Royal Purple 5W-30 High Mileage Synthetic Motor Oil
  2. Valvoline High Mileage Motor Oil SAE 5W-20
  3. Castrol GTX High Mileage 5W-30 Motor Oil
  4. Castrol EDGE 5W-30 Advanced Full Synthetic Motor Oil
  5. Pennzoil High Mileage Conventional 10W-40 Motor Oil
  6. Pennzoil Platinum Full Synthetic 5W-30 Motor Oil
  7. Valvoline Hybrid Vehicle Full Synthetic SAE 5W-30 Motor Oil

So, let’s get started!

best motor oil for cars over 100k – at a glance

In this part, we will take you through some tested and trusted oil used by most automotive experts around the globe. Importantly, I have collected performance data and other related stuff in a synchronized order, which will help you pick the perfect one easily.

#1- Royal Purple 5W-30 High Mileage Synthetic Motor Oil

Is your car consuming more oil than before? Looking for a solution? Then Royal Purple motor oil is exactly what you need! Indeed the perfect one for old vehicle engines.

Lower Viscosity:

Viscosity indicates the thickness of the oil. In the case of high mileage oils, we prefer thinner ones. Thin oils protect the parts from friction and can easily be poured. Moreover, thin oils can quickly start a car in even freezing temperatures. And this oil is the same. The lower the viscosity, the more is the efficiency!

Reduce LSPI:

Here PSPI stands for Low Speed Pre-Ignition. The oil bears many chemical additives, which can improve the work efficiency of old engines. LSPI is a common problem of older engines, and this can even damage your whole engine due to unwanted combustion. Hence, the oil reduces the occurrence of frequent LSPI and protects the engine accordingly.

No Corrosion:

I can claim it as the best oil for cars over 100k as it isn’t corrosive at all. Other oils destroy the parts coming in contact with it as they’re highly corrosive ones. So, this oil creates absolutely no rust in pistons or camshafts.

Protection from Exhaust Gases:

Gas emissions are really harmful to the environment as CO2, CO and many other toxic gases are emitted in this process. So, the oil reduces the harmfulness of these gases and protects the equipment related to the process.


  • Anti-Corrosive
  • Keeps the engine going even in cold weathers
  • Reduces environment pollution
  • Reduces LSPI


  • It doesn’t play a remarkable role in sludge removal

#2- Valvoline High Mileage Motor Oil SAE 5W-20

Valvoline Motor oil is the seal to all the leaks! The additives present in it can tackle any problem coming to your engine.

Reduced Oil Consumption:

Usually, cars over 75000 miles tend to burn off much oil as the seals deteriorate in the long run. Hence, you’ll need to refill now and then. But this oil repairs the seals and saves much oil from leaking or burning off. So, the oil consumption gets reduced on a great scale.

Anti-Wear System:

In older engines, the metallic equipment does not remain the same. Either the surface gets dry or rusted. In that case, this oil is a medicine to the equipment! 

The oil gets into every nook and corner, making the surface smooth and not letting the parts rust. So, the total anti-wear system increases the life span of your engine!

Prevent Leaks:

The most common phenomenon in HM engines is that they start to leak after 15000-20000 miles if you haven’t switched to HM oil yet. So, this is an HM oil that has seal conditioners to seal the leaking portions and saves your engine from exhaust emissions.

Maximizes Engine Life:

The engine is a substantial part of a car. And the overall longevity of an engine depends on the oil you provide. This is the best oil for high mileage vehicles as it maximizes the engine life with the additives present in it.

In addition, the seal conditioner, the lower viscosity coefficient, and the authenticity together keep fresh for long.


  • Reduces oil consumption
  • Rejuvenates the seals
  • Maximizes engine’s life span
  • Prevents leak


  • Cannot keep the engine warm in winter

#3- Castrol GTX High Mileage 5W-30 Motor Oil

If you’re facing catalytic converter problems, Castrol GTX Motor oil can be the savior! The oil has diverse features that are going to meet all your demands regarding HM oils.

Reduced Phosphorus:

Phosphorus is the reason for the early deterioration of catalytic converters. Phosphorus mixed in the HM oils acts as catalyst poison for the converters. Hence, this brand has considered this issue and provided less phosphorus in its chemical composition. So, you’re saved from paying high bills in the workshops!

Superior Detergency:

As detergents decrease the surface tension of the molecules, similarly, this oil reduces the surface tension of the deposits coming from the incomplete combustion. Consequently, the unnecessary chemicals do not interfere in the engine operations, keeping your engine fit and fine!

Synthetic Type:

Natural ingredients are present in this oil, and hence it’s synthetic type. The benefits are uncountable. such as; Low maintenance type, keeps the engine warm in winter, lubricates well, etc. Besides, synthetic oils are free from contaminants, unlike conventional ones.

Removes Sludge:

Sludge is the extra layer on the engine formed due to contaminated oil. Basically, it’s a gelatinous substance that ruins your whole engine system. As this oil is synthetic, it bears the least possibility of contamination. Thus, it prevents sludge formation.


  • Keeps the catalytic converter fine
  • Lubricates well
  • No contaminants
  • Prevents sludge formation


  • It’s slow in repairing the seals

#4- Castrol EDGE 5W-30 Advanced Full Synthetic Motor Oil

The fluid technology in Castrol EDGE oil increases the lubricant’s strength, making it the best oil for cars over 100k miles. Let’s know more!

Protects Catalytic Converter:

Like the previous model of this brand, it’s composed of really less phosphorus, which saves the converter to a great extent. Again, it’s a familiar yet very useful property of these two oils. Thus, you’re saving the whole engine by only choosing the right lubricant.

Reduces Film Breakdown:

Film breakdown refers to the degradation of oil’s strength. Your motor oil can degrade for many possible reasons like oxidation, contamination and many more. Hence, this oil has a fluid tech with which it prevents the degradation of oil and maintains a lower viscosity level. So, it ensures the best oil additives for high mileage engines.

Restores Engine Parts:

The engines over 75K miles need great oil to look after the engine parts. In older engines, problems like seals wearing off, increasing friction between the surfaces, and formation of sludge are seen.

If not treated with a suitable oil, these can damage the camshaft, pistons, and even the catalytic converter. And so this oil is a must as it contains all the essential additives required to keep the engine fit.

Contain Antioxidant:

Oils can easily oxidize if they contact oxygen; from air or water. Oxidized oil is considered contamination that gets degraded quickly and damages the whole engine. This oil has antioxidants in it to save you from all these unwanted scenarios.


  • Fuel economy increases
  • Contains antioxidant
  • Elevates the strength of oil
  • Less phosphorus saves the converter


  • Oil consumption is more

#5- Pennzoil High Mileage Conventional 10W-40 Motor Oil

An all in one lubricant compatible with not only HM cars but also trucks and vans. I’ll highly recommend this oil from Pennzoil! for older engines.

Higher Compatibility:

It’s tough to select a specific oil for a car, truck and van at the same time as all these bear different engines with different requirements. But this lubricant is just amazing. That’s because it’s compatible with every vehicle having the standard type of engine. So, you can select the oil without any doubt.

Cleans the Engine:

The only dirt present in any engine is the sludge and other similar deposits formed due to oil contamination. It has proved itself as the best motor oil for cars over 100,000 miles by cleaning the engine very precisely. The oil removes the sludge or other dirt’s and dissolves them, making the engine clean and tidy.

Conventional Oil:

The oil is not synthetic but conventional! Traditional oil is mainly extracted from crude oil through chemical processes that maintain fluidity and thickness. These types of oils can tolerate much heat, yet they aren’t suitable for HM engines. Because HM engines require oils that can protect the engine through its chemical compositions.

Increases Mileage:

A perfect lubricant can surely increase a car’s mileage. And the more you change the oil; the better it will be for the engine. But in this case, you don’t need to change the oil frequently as it works well for many days at a stretch. 

Moreover, the oil gets into every corner of the engine and restores all the wear and tear. Hence, it keeps the engine fresh and efficient, increasing the mileage accordingly.


  • Highly compatible
  • Dissolves all the dirt in it
  • It has a balanced fluidity
  • Increases mileage


The oil isn’t suitable for engines over 75k miles

#6- Pennzoil Platinum Full Synthetic 5W-30 Motor Oil

Meet Pennzoil Platinum oil which is truly efficient at its work! It keeps your engine clean, pure inside, highly compatible and many more. So what else do you need!

Cleaner Pistons:

Like other parts of an engine, the pistons also get dirty and a fat layer of dirt forms. So, to keep your engine going for a longer period, this oil cleans all the deposits formed in any way and keeps your engine new from both inside and outside.

Protects Horsepower:

The more you use a machine, the more it requires maintenance. The same is in case with an engine. And trust me, this oil provides the overall care to your car without requiring extra cost. It gives protection from any wear and tear and keeps the engine’s horsepower the same as before.

Burns Less:

Oil consumption is a common phenomenon in old engines, especially high mileage ones. The worn out seals are the reason for this burning of extra oil. Surprisingly, this oil reduces consumption at a large rate by repairing all the problems acting as a resistance for the oil.

Pure Natural Gas:

Synthetic oils are naturally made from natural gases and not from crude. These types of oil can be easily modified by adding the required chemicals. So, synthetic oils are perfect for cars over 100,000 miles. This pure natural gas keeps the engine very lubricated.


  • Cleans the pistons properly
  • Keeps the same horsepower 
  • Reduces burning off of oil
  • Made from natural gas


  • It’s costly compared to its longevity

#7- Valvoline Hybrid Vehicle Full Synthetic SAE 5W-30 Motor Oil

Have you ever thought of high mileage oil being reasonable? Valvoline Hybrid Vehicle motor oil is such oil that provides high-quality performance at a very affordable price. Let’s discuss it elaborately!

Temperature Independent:

We often notice the change of oil in different weathers. We see the oil is very thin than necessary in summer and way thicker in winter. Viscosity is a significant factor for oils, and this oil maintains it precisely. Irrespective of the extreme temperature, the oil remains the same inside and works efficiently.

Fuel Economy:

Saving fuel is useful for us and as well as our nation. The more we can use less-fuel, the more stable we become economically . Hence, the oil of this brand upgrades the economy of fuel by burning less and repairing all the damages in the engine.

Minimizes Damage:

This oil ensures minimum damage by fixing the engine several ways. The remarkable one is the stopping of exhaust emissions. The seal conditioners make sure that there are no leakage in the exhaust pipe. The leakages slowly damage the whole engine.


The price does not go with its mechanism at all. Till now, you’ve known about all the unique characteristics of the oil, and surely you must be worried about its expensiveness.

But nothing’s to worry about at all. The price is affordable, and so you can select it as your car’s permanent companion, no doubt.


  • Upgrades fuel economy
  • Minimizes air pollution
  • Affordable
  • Thermally stable


  • The horsepower decreases significantly

When to use high mileage oil?

Not every vehicle needs high mileage oils. Mainly, the older cars and vehicles with more than 75K need it.

So, how do you understand when to switch to HM oils? When you notice the following problems, I’ll suggest you go for high mileage oils:

  • If you notice leakage of oil from the exhaust pipe.
  • If your car is making weird noises while starting it off.
  • If the engine does not starts in lower temperatures like in winters.
  • If the oil consumption is very high, and you’re to change the oil very frequently.
  • If the outer parts of the engine are rusted and dirt accumulates inside them.
  • If your car goes to the garage everyday, then the medicine is nothing else but a high mileage oil.

Conventional vs Synthetic Oil: Which is right for your car?

Being a car owner, you have to frequently come across the two words “Conventional” and “Synthetic”. And for your car’s well being, you surely need to know about them.

The differences between synthetic and conventional oil are cited below:

Conventional OilSynthetic Oil
1. Conventional oil is extracted from crude oil.1. Synthetic oil is extracted from natural gas.
2. It can’t tackle exhaust emissions.2. It reduces gas emissions to a great extent.
3. It can’t reduce oil consumption3. Upgrades fuel economy by reducing consumption of oil.
4. This oil is to be changed frequently.4. This oil can be changed lately.
5. Do not play any role in sludge removal.5. Restores engine parts by removing sludge and other dirt.
6. Thermal stability isn’t maintained.6. Thermal stability is maintained well.
7.Not suitable for vehicles over 75k miles.7. Highly suitable for vehicles with high mileage.

You can surely assume which oil will be suitable for your car from the above discussion. Synthetic oil has proved its usefulness in every way possible, starting from cleansing the engine to upgrading the fuel economy.

So, synthetic is better than conventional, no doubt.

How to maintain your vehicle after 100,000 miles? (4 things to follow)

Like every other machinery, vehicles also need to be maintained well after a certain time. And it’s not possible to take them to the garage every time.

So, you need to maintain them systematically to ensure your vehicle’s longevity. But the way of maintaining them is totally different after they’ve passed 100k miles than before.

So, to keep your car just as fine as you, all you need to do is to follow my instructions:

1. Choose High Mileage Oil:

You must choose an efficient high mileage oil for your engine. These oils have additives that enhance the older engines and provide extra support. As older engines face problems like converter failure, sludge, rusting and leaks, the high mileage oils are perfect for them.

2. Change oil Frequently:

In engines over 100k miles, dirt’s accumulate quickly in the oil. Then, again, the oil easily gets contaminated or oxidized. So, frequent oil changing is necessary to keep your engine running.

3. Tire Rotation:

Tires have many grooves, which are even. But after running for certain miles, the grooves turn uneven and reduce the tires’ functionality. So, tire rotation is important for the best outcome.

4. Routine Inspections:

To avoid bigger damages, an overall inspection of the car should be done once a month. The inspection must include checking the temperature, oil level and volume of tires. The temperature must be stable, and the oil level should be moderate.

Through it, you can understand the oil consumption every month as well.

What to look for when choosing engine oil?

You’ve understood the importance of high mileage oils in enhancing the engine by the time. But uncountable options appear in the name of high mileage oil. In that case, choosing any one of them seems too tricky.

So, to make your way easier, I’m pointing out some features without which, oil is nothing but sticky fluid:

Synthetic Type:

The best type of oil is synthetic. They’ve all the essential chemicals in them to repair all sorts of wear and tear to make your engine durable in the long run. So, don’t go for conventional ones in any way. Because though they’re a bit cheaper, they can cost you a lot by damaging the whole engine.

Thermal Stability:

Most often, the engine does not start at once. You need to put a lot of effort to start it then. It’s mainly due to the thermal imbalance of oil. So, the oils which are temperature independent, are chosen. Specifically, the ones which do not freeze in winter needs to be selected.

Seal Conditioner:

Leakage is a widespread problem that results in more oil consumption. Leakage happens due to the breaking of seals inside the engine. Hence, the oils that can rejuvenate the seals are to be selected. Rejuvenating seals upgrade the fuel economy, prevent leaks, and remove sludge.

Lower Viscosity:

Viscosity means how thick or thin an oil is. A lower viscosity level indicates the proper reaching of the oil in every corner and a sludge free engine. So, do check the levels properly on the outer skin of the container and then select your desired one.

people also ask (FAQs)

Will it help to run thicker oil in a car with over 100,000 miles?

High mileage oils prevent leakage of oil from the very beginning. Thicker oil is mainly used for reducing the possibility of leakage. But still, to increase the oil pressure, many use thicker ones.

Is full synthetic oil better?

Full synthetic oil is considered the best oil for high mileage cars over 100k miles. The reason is that they’ve all the essential chemicals in them to support the older engines.

Is 10w40 good for high mileage?

Yes, it is. The older engines can take up higher temperatures. And so, a thicker oil can be a great choice.

How often should the oil in high mileage engines be changed?

In the beginning, it’ll be great if you change the oil every 5000-7500 miles. But as the engine gets older, you’ll have to change them more frequently.


In my guide, I’ve tried to make you informed you about the best oil for cars over 100K miles. Indeed, I’ve surely been able to clear most of your doubts through my guide.

So now, you can keep your engine roaring for at least some more years longer. Do share this guide with your near and dear ones in need.

Read also:

5 Best Oil For Duramax Diesel Engines | (Boost Performance)

5 Best Oil For 5.4 Triton Reviews– (Boost Ford’s Engine)

5 Best Oil For High Mileage 5.3 Vortec Engine

Who Worked on This?



I'm the guy responsible for ensuring that every blog post we publish is helpful for our reader.

Mahir Ahmed


I'm the guy responsible for ensuring honest, informative, accurate and helpful guide to the reader.

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