Subaru Forester Owners Forum banner

1 - 20 of 35 Posts

·
Registered
2015 Forester
Joined
·
10 Posts
Discussion Starter #1
2015 Forester
I'm approaching 40,000 miles and have been doing my own oil and filter changes using 0w20 for 4 years at 3k to 5k intervals. Oil consumption is close to nil. I noticed that some owners are using 5w30 when they get up in mileage. My question is at what mileage point are people going up to a more viscous oil and is it necessary? I'm thinking somewhere around 80 to 100k but would like to hear from some forum members regarding this.
 

·
Registered
2016 2.5i Premium 6MT
Joined
·
82 Posts
As long as your oil consumption is "close to nil", you don't really need to move to a heavier oil. Owners with 6 speed manual transmissions sometimes move up to 5W-30 to lessen the oil consumption issue.
 

·
Premium Member
‘14 FXTT; '15 Legacy FB25
Joined
·
1,027 Posts
Keep doing what you're doing. There's zero reason to change your oil of choice, including viscosity, if you're not consuming any oil!

SOA dropped the oil change frequency from 7500 to 6000 miles about 2017 due to oil consumption on the tail end.

If you are keeping the 3 to 5k intervals you may not need to go with anything heavier.

Brian
2015
 
  • Like
Reactions: subatron and jasonn

·
Registered
2017 XT
Joined
·
15 Posts
I do my own OC's as well. If you want to fall down the rabbit hole on viscosity so to speak, check out here:
CAFE Standards in the US and Oil Weights
I'm of the opinion that it has more to do with startup temperature (see the Caterpillar scanned page on the above link) for the 0w vs 5w and the difference in running ambient temp based on engine cooling ability for the 20 vs 30.

The KEW page has some pretty good charts for temperature vs viscosity and making a good decision.
https://www.kewengineering.co.uk/Auto_oils/oil_viscosity_explained.htm

I'm in Phoenix, so summer time temps are kinda warm. Winter temps, I'll never see any need to require a 0w oil, even if I drive to Flagstaff to go skiing. I have the XT, so the little thicker oil (at operating temp) and associated HTHS numbers are my concern in that super speedy spinning booster thingy (turbo). I'll be running 5w-30 for the life of the car, perhaps switching to a high mileage version at 100k miles.

With the temperature vs viscosity charts available, make your decision based on data, the decision I make for my vehicle in my climate may or may not be a good one for you. Especially if you're from Nova Scotia!
 

·
Registered
2015 Forester
Joined
·
10 Posts
Discussion Starter #6
Thanks for all your input. Being up here in New England we get some pretty cold winters and warm (getting warmer) summers. The 0w20 Pennzoil Platinum I'm using gives me a little more confidence for those winter cold starts and seems to work well in the summer. I'll continue with 0w20 until the time comes when I start consuming some significant oil.
 

·
Registered
2011 Subaru Forester
Joined
·
741 Posts
Sounds like a plan. If you are into experimenting you could always try 5w30 during the warmer months, and that might provide some extra engine protection for the long haul. New England, like the Ottawa area in Canada, gets some really cold weather but also some really hot weather in the summer. My 2011 with the same engine as yours burns oil so I use 5w30. No problems starting last winter. 5w30 synthetic flows surprisingly well at low temps.
 

·
Registered
2015 Forester
Joined
·
10 Posts
Discussion Starter #8
I guess that's what I was getting at. Does 5w30 extend the engine life even though Subaru says 0w20. This is my second Subaru and the first that uses 0w20 oil. My first was a 2007 Outback which took 5w30. Did Subaru change something?
 

·
Registered
2018 Forester Manual
Joined
·
389 Posts
They are different engines. Your old Outback would have had the EJ25 engine, where this one has the newer FB25 engine. These engines were designed to use 0w-20 from the beginning. I don't believe there would be any damage done long term to using 5w-30 , especially in a higher mileage one. I stick to 0w-20 in the winter in mine for the extreme cold starts we get.
 

·
Registered
Sahuarita, Arizona USA 2018 Forester Limited
Joined
·
2,270 Posts
Sounds like a plan. If you are into experimenting you could always try 5w30 during the warmer months, and that might provide some extra engine protection for the long haul.
Or 0w30
 

·
Registered
2017 Forester 2.0i CVT
Joined
·
44 Posts
I always had a similar question in my mind....

So, bearing in mind that I live in Panamá... so that's no cold weather whatsoever actually that's an average max of 88º F and an average low of 77º F for the past year.

Wouldn't 0w20 for (in my case) the FB20 engine be too thin of an oil? on my previous car I used 10w30 and before that I had a car that used 15w40.
 

·
Registered
2015 Forester Premium CVT
Joined
·
431 Posts
I can't find a thread now but someone posted a Japanese link about Subaru's own work on the performance of different weight oils for their engines. 0W-20 was primarily good for fuel economy but the chart mentioned that 5W-30 is best for engine protection.

A couple of years ago, I switched to 5W-30 on a whim. I personally didn't notice any difference in oil consumption or fuel economy, so for the sake of consistency with another vehicle, I switched to 5W-30. I am closer to NYC.

Depending on where you are in New England, you may do just fine with 5W-30. For us, my wife hates to sit in the cold car and Forester takes significantly longer to warm up, so she always remotely starts the car 5 minutes before leaving.
 

·
Registered
Sahuarita, Arizona USA 2018 Forester Limited
Joined
·
2,270 Posts
I can't find a thread now but someone posted a Japanese link about Subaru's own work on the performance of different weight oils for their engines. 0W-20 was primarily good for fuel economy but the chart mentioned that 5W-30 is best for engine protection.
Actually it was 0w30 that provided better engine protection, and here's a similar thread from the Crosstrek forum:
 

·
Registered
2011 Subaru Forester
Joined
·
741 Posts
Actually what persuaded me to use 5w30 was reading on this forum that only North American vehicles use 0w-20. My impression was the same Forester sold in Asia, Europe or Australia say to use 5w-30 and I think even 10w40 in tropical climates. And also that Japanese Subaru site that showed the different types of oil Subaru uses and the conditions to use them in. The FB25 was not designed to only use 0w-20.
 

·
Registered
2017 XT
Joined
·
15 Posts
The above link from KEW engineering is a good explanation of viscosity, in particular the KV100 and KV40 and graph 4 near the bottom of the page. When you are starting in the winter at a cool temp, say 0 deg C and your KV for 5W oil is 80-100 cSt but at operating temps (say 200C) 20, 30, 40 and 50 weight are within 10 cSt of each other I'd say the KV at the warmup stage and your application of the noise pedal are the most important. The Viscosity Index Improvers in synthetics are apparently better than the ones of old. Fuel dilution in modern injected engines is way less of a factor than in the carbureted engines I grew up with - and the exhaust is so much less offensive thankfully.

In the US, the owner's manual must state the recommended oil for the engine based on the oil viscosity used to obtain the EPA mileage estimates. (see post number 5 below)

Oil Viscosity, CAFE, and your Taco Engine

My concern with the FA20 DIT engine in my vehicle is less the starting and ending viscosity of the oil but the Dexos 1 Gen 2 (or GF-6, SN+) rating for LSPI. Ideally we would have a -5w40 oil that maintained ~13 cSt viscosity from -10C to 200C. But the amount of VII's to do that and maintain an OCI of 10,000 miles just doesn't exist yet.

Actually what persuaded me to use 5w30 was reading on this forum that only North American vehicles use 0w-20. My impression was the same Forester sold in Asia, Europe or Australia say to use 5w-30 and I think even 10w40 in tropical climates. And also that Japanese Subaru site that showed the different types of oil Subaru uses and the conditions to use them in. The FB25 was not designed to only use 0w-20.
The questions I have are: what cSt assumption vs design life was used when the engine specs were being put together. (There's gotta be a number of limit curves defining that vs cost of warranty claims and public perception of longevity). Can I cheat the design life out of the curve by using A or B oil? Or is the fuel I use more important? Or is the average ambient temperature? Anyone work at Fuji Heavy Industries?
 

·
Registered
Joined
·
2 Posts
2015 Forester
I'm approaching 40,000 miles and have been doing my own oil and filter changes using 0w20 for 4 years at 3k to 5k intervals. Oil consumption is close to nil. I noticed that some owners are using 5w30 when they get up in mileage. My question is at what mileage point are people going up to a more viscous oil and is it necessary? I'm thinking somewhere around 80 to 100k but would like to hear from some forum members regarding this.
Stick with 0-20 oil forever, these people who change to 5-30 well start having valve problem.
 

·
Registered
Joined
·
11 Posts
2015 Forester
I'm approaching 40,000 miles and have been doing my own oil and filter changes using 0w20 for 4 years at 3k to 5k intervals. Oil consumption is close to nil. I noticed that some owners are using 5w30 when they get up in mileage. My question is at what mileage point are people going up to a more viscous oil and is it necessary? I'm thinking somewhere around 80 to 100k but would like to hear from some forum members regarding this.
FYI, MrSubaru1387 youtube channel has a video where he says in Japan all Subarus are filled with 5w30 and the Japanese owner manuals also say 5w30. 0w20 is used in the American market by SOA to meet MPG levels.
 

·
Registered
2014 Forester Touring 2.5 CVT
Joined
·
152 Posts
2015 Forester
I'm approaching 40,000 miles and have been doing my own oil and filter changes using 0w20 for 4 years at 3k to 5k intervals. Oil consumption is close to nil. I noticed that some owners are using 5w30 when they get up in mileage. My question is at what mileage point are people going up to a more viscous oil and is it necessary? I'm thinking somewhere around 80 to 100k but would like to hear from some forum members regarding this.
Hi, please do not consider changing viscosity for any reason. Just because it's more of viscous doesn't result in less oil consumption using a higher viscosity grade. Subaru, like all brands, design engines around the viscosity number chosen for economy and longevity. It has been shown that higher viscosity use will slow oil velocity in oil runners and ports which results in increased sludge. There is no reason to not listen to the engineers.
 

·
Registered
Joined
·
9 Posts
Changing the oil viscosity can actually backfire on you. When engines are designed, the passages for oil near shaft seals are designed to reduce the static pressure of any oil return next to the seal. If you raise the viscosity but don’t change anything else, more oil will accumulate at the seal surface, increasing the pressure to push oil past the seal lip. Don’t do it.
 
1 - 20 of 35 Posts
Top