Poor MPG for my 2006 2.5T S60 at 89K

[RSAmbassador]

I have a 06 2.5T FWD I recently changed one coil, a fuel pressue sensor and plugs and went from 18 mpg to 20mpg driving through the mountains of Eastern Kentucky

[vtl]

I'm very interested in the technical details of how the new SPA T8 drivetrain behaves

Yes, fuel economy is very important when you pay $75k+ for a car.

[vtl]

Do you mean mileage got better or worse after the oil changes?

Thicker oil = better drive train protection = lesser MPG.

[mrbrian200]

My mileage dropped a lot after replacing 75w90 with 75w140 in bevel gear and 5w30 with 10w40 in engine.

Do you mean mileage got better or worse after the oil changes?

Its the bevel gear that did it. Gears are submerged. The gear teeth grab the oil and circulate it around the housing. Higher viscosity = resists circulatory flow which imparts resistance against moving parts. And that oil is moving around in there probably a lot faster than you think.

You're probably trying to extend the life of the unit by switching a heavier oil. Also consider the increased viscosity/resistance would generate more heat

You might have better luck with an OE specified viscosity very high quality group 5 aviation oil + a PTFE additive.

[vtl]

Its the bevel gear that did it. Gears are submerged. The gear teeth grab the oil and circulate it around the housing. Higher viscosity = resists circulatory flow which imparts resistance against moving parts. And that oil is moving around in there probably a lot faster than you think. You're probably trying to extend the life of the unit by switching a heavier oil. You might have better luck sticking to OE specified viscosity very high quality group 5 aviation oil + a PTFE additive.

Yes, switching to 75w140 (Amsoil) had a significant effect on car's ability to accelerate. However, we had a couple of really hot summers, so I feel that viscosity already broke down. I have a jug of OE 31259380 oil, will drill the drain hole and just be doing oil changes more frequently. Interestingly, I don't see the bottle saying 75w90 any more, it says: for bevel gear and rear differential. The latter actually runs on a plain SAE80.

The other interesting observation is switching from Amsoil Signature 0w40 (PAO mostly) to Red Line 10w40 (esters mostly) had a similar effect, like weight 140 oil in bevel gear. Car is a lazy dog with it, really. More quiet too

I'm not trying to extend anything, life or OCI, I just had a feeling that w30 is too thin for an engine developed at the end of 80s, and know for sure that w90 in bevel gear looses viscosity too quickly in hot days with a lot of highway driving. Don't drive that much any more, don't need extra protection, will go back to 10w30 or something.

[chrism]

When I was looking for a S60 I specifically ruled out AWD ones. You couldn't have given me one I would have just sold it and used the money to buy a FWD.

And your profile places you way north. I live in TX and I can't believe how many of the Volvo wagons around here are AWD - we have one icy day every two years. And to your point, the used car prices on Craigslist, etc, (at least in my area) don't give the AWDs any favoritism.

[mrbrian200]

I'm very interested in the technical details of how the new SPA T8 drivetrain behaves

Yes, fuel economy is very important when you pay $75k+ for a car.

For a 1st new car private owner, probably not.

Fleet sales.. yes econ can factor into decision making. 54 cents/mile is a fixed rate deduction.

10 years down for 2nd/3rd private owners, fuel economy becomes more of a primary concern. It was for me.
Of competing models I initially considered with a cash budget for mid-late 2000s, smaller MB and BMWs of the era, which are certainly nice cars I could have been happy driving around, specifically got bounced from consideration because of terrible highway econ. Somewhere I caught real world reports of the FWD 2.5T Volvo sedans approaching 40mpg on the highway. Did my research, its a rock solid drivetrain so long as you practice common sense maintenance. So tracked out I looked at one....instantly loved it inside and out. But not a P3: exterior contours/styling on the P3 sedans do nothing for me. But they're getting that back with the SPAs.

[mrbrian200]

The other interesting observation is switching from Amsoil Signature 0w40 (PAO mostly) to Red Line 10w40 (esters mostly) had a similar effect, like weight 140 oil in bevel gear. Car is a lazy dog with it, really. More quiet too

I'm trying to figure out what specific base oil(s) are used in Quaker State Ultimate Durability 5w30.
Googling I'm not finding a definitive answer, just people appearing to speculate what it might be and, though it likely has some PAO to meet GM4718 the primary base oil is something else not PAO. Question is what?

My car didn't like Amsoil Signature 5w30. Tappet noise was ridiculous, I could hear it inside the car. And econ wasn't consistent except on longer drives it would perk up after 20 miles or so. With QSUD I get the good econ as soon as the engine is warm/1 mile (like it was first week before draining unknown oil) and I never hear top end noise inside the car unless I open the bonnet...barely hear it standing right in front of the car idling with the hood closed. Mine acted like a lazy thirsty dog with Amsoil.

[vtl]

10 years down for 2nd/3rd private owners, fuel economy becomes more of a primary concern.

Buy economy car then. Mighty and thirsty 2.5T is mighty and thirsty even 10 years later

So tracked out I looked at one....instantly loved it inside and out. But not a P3: exterior contours/styling on the P3 sedans do nothing for me. But they're getting that back with the SPAs.

SPA was released too early. It has some real mechanical problems.

[vtl]

My car didn't like Amsoil Signature 5w30. Tappet noise was ridiculous, I could hear it inside the car. And econ wasn't consistent except on longer drives it would perk up after 20 miles or so. With QSUD I get the good econ as soon as the engine is warm/1 mile (like it was first week before draining unknown oil) and I never hear top end noise inside the car unless I open the bonnet...barely hear it standing right in front of the car idling with the hood closed. Mine acted like a lazy thirsty dog with Amsoil.

Mine was going through Amsoil SS 5w30 too quickly. Must be piston rings. Also noticed tappet noise. Same oil in wife's new XC60 with B5254T12 is fine: no consumption, no tappet noise.

The other thing I really didn't like about Amsoil SS: it cleans engine so-so. When I did camshaft seals, all engine surfaces contacting with oil were covered by varnish. This was the main reason I decided to try esters-based oil. I used a regular mineral based Amsoil in V70 with N/A engine, it did amazing job cleaning everything out. And I got V70 in a much worse condition than XC70.