Using 0W-20 to replace 5W-30

Status
Not open for further replies.
K

Kralik

Joined
Aug 5, 2007
Messages
25
Location
Oregon
So, I've decided to take a risk using Amsoil's new 0W-20 oil in an engine whose recommended grade is 5W-30. My main motivation is fuel economy. I drive a 1994 Geo Metro which currently gets 55mph, mostly highway miles; my goal is 60. I know there's a lot of debate on the thin oils issue around here, but from what I understand here are some reasons for it:

-Amsoil's 0W-20 is on the thick end and close to 5W-30 specs.
-Conventional 5W-30 oils from the 90's typically sheared close to a 20 weight anyway.
-Synthetic oils have good antiwear additives.
-Try it, do a UOA at 5k, and see what you get.

Reasons against:
-Can shorten your engine life, depending on your engine.
-Can cause more wear, depending on your engine.
-Why not just stay with the recommended grade?

I'm sure there are more pros/cons but those are a few that I remember. What I was wondering is... what should I be looking out for to see if I should change back to 5W-30? Any warning signs/sounds? Or was this all a bad idea to begin with and I should switch back before I hurt something?

For the record, I drive in Oregon, which rains around 3/4 of the year and stays relatively cool in the summer. I never speed--usually I go slightly below highway speeds. There are a few hills around my house that give the car a workout.
 
If you getting that kind of mileage you being vary careful and that's probably going to give the oil an easy job of keeping up. Amsoil's 0w-20 is an excellent oil, have no worries.
 
Since your plan is to use one of the best, it should work well. Don't fear anything.

What fluids are you running in the trans? PSF?....

If there is room, a bigger oil filter can be fitted. A few extra ounces of oil capacity along with bigger filters surface area for cooling, should also help.
 
NO NO NO, Yes 5w20 will work in this engine, but since it is a 1994 and has never seen 0w20 don't you think bearing journals and clearances are conditioned to Xw30 oil. Why would you risk the engine of car that gets 55mpg! No need! C'mon I'll bet you haven't you noticed the price of little cars such as your Geo goin' up. They used to be everywhere for $500 now I see um for thousands what are you thinking????
Why risk an engine that gets 55mpg... Try Amsoil 5w30 it is synthetic and you will still have peace of mind...
 
Thanks for the responses so far! A little more background:

I bought the car used last month for $700 (a steal IMO) with 135k miles. The lady who owned it took good care of it--she knows very little about cars but had it serviced at her mechanic every 7500 miles, with religious OC's every 3k. They have all the maintenance records. No major repairs done, but it looks like for whatever reason they never saw fit to change the coolant over 13 years.
dunno.gif
She was getting 42-47 mph with it, but I've been able to improve that mostly by driving techniques (being careful with the gas pedal, watching ahead for red lights, driving the speed limit, etc). Manual recommends OCI's every 7500 miles with filter changes every other OCI for normal driving, 3k for severe.

unDummy--The manual transaxle lubricant is OEM. The car's manual calls for 75W-85 GL-5, but I was hoping to replace it with synthetic. Amsoil's product recommendation gives 75W-90 GL-4 and their tech support thinks it might have been back-spec'ed. Do you know if GL-4 can replace GL-5? For oil, I'm using Amsoil's EaO filter, which is quite small (the normal size for the car - holds 0.2 quarts).

Camu--Are you saying then that switching to 0W-20 would have been fine if it had been when the car was new? Obviously I want the engine to last a long time. Wouldn't a xW-20 flow better than a xW-30, reducing start-up wear? The ASM specs are close to 5W-30 minimums: 2.8 HT/HS vs. 2.9, 9.0 cST @ 100 deg C vs. 9.3... Since the oil's already in there, any thoughts of what to look for if it IS damaging the engine?

Pablo--I should have thought of that.
pat2.gif
How long should I wait before doing a UOA now? 5k? 10k?
 
If the coolant hasn't been changed in 13 years I'd take it to a shop that can do a complete chemical flush, then a complete flush with distilled water, and then refill with 50/50 DexCool (if that's what it came with) or any Long Life coolant if it didn't come with DexCool.
 
You require a GL5 75w85. Good luck finding one. Funny, because I don't remember 85 being a weight way back then.

GL4 and GL5 don't replace each either.

Since MPG is the goal, I would think that the Redline MTL or Amsoil MTF would work well enough alone. Even though not rated for GL5, these 2 GL4 manual fluids have pretty stout additive packages.
Simple mixing Redline MTL/MT90 or Amsoil MTF/MTG 50:50 should give you an 85wt full synthetic.
I doubt that the monster engine can even stress the transmission too much, and don't see the GL rating as an issue.
Another option is the Redline Shockproof gear oils.
 
I personally don't see any reason not to try 0W-20 but I think the primary benefit (over 5W-30) will be when it get's colder, not now. I would also recommend changing out the OEM lubricants, using something synthetic instead. Redline and Amsoil both make good products.
 
Quote:

You require a GL5 75w85. Good luck finding one. Funny, because I don't remember 85 being a weight way back then.

Click to expand...


You know, I was going off of a Haynes manual (I don't have the original owner's manual) Browsing around online I am finding lots of differing opinions and it might be either GL4/GL5. I'll have to keep searching.
 
The beast requires a GL4. No call for a GL5. Just use MTG or if you really want to go for MPG, mix MTF/MTG 50/50.

As for OCI. Just do 5K. The engine may not be clean, but 5K will be no problem.
 
The Haynes manual must be giving false information. Found GL4 as the right type in many other places online. I'm sure that's what happens when you print a one-size-fits-all manual for a car that was manufactured from 1985-2001.

I ordered 3 quarts of MTG from Amsoil but it's currrently on backorder. Do you think they would let me change it to 2 quarts MTG and 1 quart MTF? (The total capacity is about 2.5 quarts) What is the rationale behind mixing the two that makes for better MPG?

Also, is that a recommended 5k OCI on Amsoil's 0W-20 simply because it's the first go with synthetic, a lower weight than normal, or...? I thought the oil would be generally good for 10k-15k.
 
Quote:

I ordered 3 quarts of MTG from Amsoil but it's currrently on backorder. Do you think they would let me change it to 2 quarts MTG and 1 quart MTF? (The total capacity is about 2.5 quarts) What is the rationale behind mixing the two that makes for better MPG?

Click to expand...


Yeah call first thing in the AM and you can change the order. The rationale is to thin the MTG (vis about 14) with MTF (about 9.6) - this won't seriously compromise protection and should help eeeeeeek out a little more MPG.

Quote:

Also, is that a recommended 5k OCI on Amsoil's 0W-20 simply because it's the first go with synthetic, a lower weight than normal, or...? I thought the oil would be generally good for 10k-15k.

Click to expand...


Yes, both. There WILL be some serious cleaning going on the first change. You could take it to 10K, but watch the consumption!
 
It looks like the MTF actually matches the GM part number (12345349) that I've been seeing for the factory fill on the Geo. Unless there's a good reason not to (I'm new and open to suggestions!), I think I'll go ahead and change the whole 3 quarts to the MTF.

I did try the Amsoil Engine Flush before switching oils, but it did not seem to do that much (the new dino oil that was in there turned medium brown). I will watch consumption - I check my oil levels weekly. Could I expect 10-15k OCI's after the first go? Thanks!
 
Quote:

It looks like the MTF actually matches the GM part number (12345349) that I've been seeing for the factory fill on the Geo. Unless there's a good reason not to (I'm new and open to suggestions!), I think I'll go ahead and change the whole 3 quarts to the MTF.

I did try the Amsoil Engine Flush before switching oils, but it did not seem to do that much (the new dino oil that was in there turned medium brown). I will watch consumption - I check my oil levels weekly. Could I expect 10-15k OCI's after the first go? Thanks!

Click to expand...


A bit odd on the tranny - but if the part # matches - yeah go 100% MTF. 10-15K is very doable with a clean engine.
 
Quote:

If the coolant hasn't been changed in 13 years I'd take it to a shop that can do a complete chemical flush, then a complete flush with distilled water, and then refill with 50/50 DexCool (if that's what it came with) or any Long Life coolant if it didn't come with DexCool.

Click to expand...


Thanks for the advice, G-MAN, I'll look into flushing the coolant ASAP.
stirthepot.gif


An observation regarding 0W-20: Unless I'm just imagining things (paying more attention to my car than normal
crazy.gif
), it seems like it is much quieter in higher RPM's and during engine braking than with xW-30. When I would downshift to 3rd gear going 35 mph, I used to really hear it; now it's not that noticeable. Is that a good or a bad thing? I don't have a tachometer, but perhaps the engine is working at lower RPM's as a whole?
 
Quote:

You can get 60mpg from your car the way it is right now. Just get a Scangauge and drive according to it.

Click to expand...


Scangauge only works for 1996+ IIRC, but I think there are other options.
 
Status
Not open for further replies.

Similar threads

Redhawk454
0w-30/5w-30 in a 2024 crosstrek and subaru timing chains
3 4 5
Replies
89
Views
10K
Redhawk454
T
Instrumented Fuel Economy Test - 0W-20 vs 5W-30
Replies
10
Views
5K
wemay
Z
Do you need better base oil to make 0w oils?
Replies
9
Views
844
dumkid
Jordan_FX4
2022 Toyota Tundra 3.5 iForce Oil Selection
Replies
12
Views
500
Graham Piccinini
R
Motul 8100 0w-20: Eco-Lite vs Eco-Clean (or anything else)? For Citroen C1 (Toyota Aygo)
Replies
11
Views
1K
vinu_neuro
Back
Top