Running the right oil and oil filter in your second-generation Subaru Forester (Forester SG) is important to maintain proper function and extend the life of its engine. Using the incorrect oil and/or oil filter can lead to an increased rate of wear and in some extreme cases, possibly even total engine failure.
Another important thing is to make sure that both the oil and oil filter are changed at or before the recommended service intervals outlined by Subaru.
In this guide we have put together some information on some of the best engine oils and filters for the second-generation Subaru Forester. We have also included some answers to some common oil related questions such as when to change the oil and oil filter. Read on below!
Table of Contents
What Is the Correct Engine Oil Weight for a Subaru Forester SG?
In this section we have put together some information on how the oil classification system works and what it means for your Forester SG.
The number/letter at the front of the “XW-XX” classifications indicates the oil’s viscosity at – 17.8 degrees Celsius (0 degrees Fahrenheit). A lower number means that the oil will thicken less in cooler temperatures.
The two numbers at the end (XX) indicate the viscosity of the oil at 100 degrees Celsius and represent the oil’s resistance to thinning at high temperatures.
If we compare a 5W-30 grade oil vs a 10W-30 grade we will find that the former thickens less in colder weather. However, a 5W-30 grade will thin out quicker at higher temperatures than a 5W-40 grade oil for example.
What this means for your second-generation Subaru Forester is that an oil with a lower winter viscosity (XW) is probably better for colder operating temperatures or environments. For those of you who are located in a really hot environment, an oil with a higher viscosity at 100 degrees Celsius may be a better option.
What Is the Best Engine Oil for a Second-Gen Subaru Forester?
A good quality 5W-30, 10W-30 or 10W-40 is recommended for most driving conditions and will be perfect for your Forester SG. If you are in a colder environment and want better protection on engine start-up, many owners recommend a 5W-30 engine oil. For those in really hot places or those who regularly track/drive their Forester hard and have a modified engine, something like a 10W-50 engine oil may be beneficial (but is not really recommended for general driving and stock setups).
Both non-synthetic (dino) and synthetic oils will work, but these days it is generally recommended that you use a good quality full synthetic in one of these cars. Non-synthetic oils will need to be changed more frequently than synthetic oils.
Our Recommendations for the Best Engine Oil for a Forester SG
Below you can find some of our top recommended oils for a second-generation Subaru Forester.
Castrol Edge 5W-30 Advanced Full Synthetic – Best for Cold Weather & Great for General Use
For those looking for a great synthetic oil for cooler environments and starts, Castrol Edge’s Advanced 5W-30 Full Synthetic is a great option. It is Castrol most advanced engine oil and will be perfect for those who need maximum protection and performance for their Subaru Forester SG. This oil will also still be great for general use conditions and most operating temperatures as well.
Mobil 1 10W-30 Full Synthetic – Great for General Use
If you are looking for a great engine oil that will be suitable for most driving conditions than you can’t go far wrong with Mobil 1’s 10W-30 Synthetic Motor Oil.
Valvoline MaxLife 10W-40 Synthetic – Best for Hot Weather & Harder Driving
A good quality 10W-40 synthetic like Valvoline’s MaxLife 10W-40 is often recommended for hotter environments and harder driving conditions. Additionally, some owners of high-mileage Forester SGs have found that a 10W-40 engine oil performs better than something like a 10W-30 or 5W-30 weight oil. If you live in a place like the United Kingdom where it is a bit colder, a 5W-30 oil like the Castrol above is probably a better option.
There are plenty of oils on the market that will be perfect for your second-generation Subaru Forester, and the ones above are just a taste of some of the many. Brands such as Amsoil, Motul and Fuchs provide great solutions, so you should check out them as well. Oils with a weight of 5W-30 or 10W-30 are probably going to be the best for the majority of Forester SG owners, but a 10W-40 will be great for those in hotter environments.
When Does the Oil Need to be Changed on a Subaru Forester SG
Different owners will give different answers on when to change the oil in a Forester SG. Subaru initially recommended changing the oil (synthetic) every 12,000 km (7,500 miles) for normal use for all models, but later cut that in half to 6,000 km (3,750 miles) for some of the models in the Forester range (mainly turbocharged models). This reduced service interval is also recommended for severe driving conditions.
Many enthusiastic owners, especially those with turbocharged Foresters like to change the engine oil closer to the 6,000 km (3,750 mile) mark even on synthetic oil. For those that don’t drive much the engine oil should be replaced every 12 months regardless of mileage.
For those wondering if their second-generation Forester can go a bit further between changes, we recommend that you send the old oil in your Subaru off to a laboratory where its condition can be assessed. The lab will then be able to tell you if you can go further between changes or if you need to make changes more frequent.
How Much Oil is Needed for a Forester SG?
This can be a somewhat confusing topic and really depends on the engine your second-gen Forester has and whether or not you are replacing the filter (we recommend that you do). Below you can see what each engine roughly needs for a replacement (with filter).
| Engine | Capacity (with filter replacement) |
| EJ 20J 2.0 | 4-litres (4.2 qt.) |
| EJ 20 2.0 Turbo | 4.5-litres (4.7 qt.) |
| EJ 253 H4 2.5
| 4.2-litres (4.43 qt.) |
| EJ 25 2.5 | 4.2-litres (4.43 qt.) |
| EJ 25 2.5 Turbo | 4.3-litres (4.54 qt.) |
We recommend that you use the above as a general guide and then use the dipstick to make sure that the level is correct. Add more if needed as running these cars with too little oil can cause major issue, especially on turbocharged models.
Oil Filter for a Subaru Forester SG
There are loads of different oil filters available for the second generation Forester, but the most recommended one tends to be the Tokyo Roki/Subaru 15208AA100 that is black in colour. The 15208AA100 is usually recommended over the other OEM filter, the Honeywell/Subaru 15208AA12A that is blue in colour.
When it comes to good aftermarket options something like the Mobil1 M-108 or the WIX 57712 comes highly recommended. You can read more about a full comparison of the different oil filters for an SG Forester here.
When Should the Oil Filter Be Changed?
It is generally recommended that you replace the oil filter with every oil change (especially as they are fairly cheap to purchase). Oil filters are cheap and overtime the filter media can break down, especially if it is submerged in oil for a long time.
If you are interested in buying a Subaru Forester SG or want to know about any more common problems, check out our buyer’s guide here.
