Mobil1 5w30 vs 15w50 question.

[coffee]

Hi All,

As some of you know my Volvos both recommend 5w30, 10w30 and 15w40 depending on the season/climate. A lot of posts in recent times state that lower grades provide tremendous protection for all climates. Presently I am using 5w30 and have a question. Does 5w30 provide adequate protection for Arizona weather and my older vehicles with higher miles or would 15w50 be better protection with the loss of fuel economy? I am only considering these two oils right now so please try and answer accordingly as I am not really looking to compare other grades. I just wonder why my Volvo has such a wide range of oil grades and why 5w30 would not protect enough and why 15w50 would even be needed for any application. Thank you.

 

[aquariuscsm]

My last car and present car(3000GT and 300ZX)both listed a wide range of oil grades..........10W30-20W50. My 300ZX FSM warns against using 5W20-5W30,and says do not use them in the turbo model. The 3000GT`s FSM said to use a 10W40-20W50 if you do alot of sustained high speed driving/commutes.

Best performing oils(smoothest/quietest acceleration and throttle responsiveness)I`ve used in my Z are a tie between M1 15W50 (silver cap) and RP 15W40,which is what I`m presently running.

 

[coffee]

Thanks for the input and I am leaning towards the Mobil 15w50. My 1985 244GL has 340k and my 1994 945 has 136k so the thicker oils may be better.

 

[aquariuscsm]

I know a guy here who has a Z32 twin turbo that`s run nothing but 20W50 GTX all it`s life and he`s nearing 400k miles. Some engines like the thicker oils and some don`t it seems.

 

[Merkava_4]

Quote:
I am only considering these two oils right now so please try and answer accordingly . . .


LOL!

 

[JAG]

cofee, I think you got it right when you used Mobil 1 5W-40 TDT (if my memory serves me right that it was you). If it was you, why did you change?

 

[coffee]

Yes, I tried that oil a while back but kept reading and getting convinced to try thinner oils. I get concerned that the thin oils may be bad for my higher mileage Volvos even though I do not see any consumption so I started looking at thicker oils again. I think the thinner oils can handle the Arizona heat but wonder more if my Volvos can handle the thinner oils over time.

P.S. hehe, thanks for catching that, Merkava.

 

[aquariuscsm]

My old neighbor had an `85 Volvo (can`t remember the model) and the oil filler cap said "Use Castrol GTX 20W50".

 

[coffee]

That is interesting, Aqua. I wonder what model that was. My filler caps do not say anything but the manual as I stated gives a 5w30-15w40 range. I love the way the cars feel when using a lower grade and the gas mileage is better but I just want to make sure not to increase the wear as well as damage anything by using too low of a grade. It never gets lower than 40 degrees in the winter here and of course gets to 115 degrees in the summer so I guess Mobil 1 15w50 would be fine year around if I go that direction.

 

[Curious Kid]

Would you feel better having installed an oil pressure gauge. I know one person hat runs a VW site writes something alone the lines of being nothing more than for entertainment value - inaccuracy. I'll admit that they are not 100% accurate, but then again what is? I would also not use the gauge alone to figure what's safe for viscosity alone when venturing outside of OEM recommendations.

Is your concern for too light a grade of oil founded, or just one of those nagging fears that seems shared amongst the lot of us?

My '95 850 recommends the same visc. range of 5/10w30 - (5?)15w-40, for SH API flavor IIRC. Oils have improved, to the point of being able to use 5w-30 above the ambient temp recommendation of 68f? The engine in this vehicle is DOHC, so start visc. for the lifters/cams is a limiting factor in the cold, though some have pointed to failing seals for the oil pick-up/ways is the culprit. I think I sound like a broken record in that department - sorry for that. As you can tell I have my issues also.

why not try for a UOA if for nothing else than finding is a 15w-40 is capable for your vehicles? 300k in one vehicle might not be like 300k in another, especially depending upon the degree of engine maintenance and driving cycles. But then again I wouldn't know what 300k is like as I'm on my 2nd vehicle - the first became a mindful of maintenance issues of 20yrs and a hand-down.

Take care and congrats on ownership successes in terms of going the distance.

 

[coffee]

An oil pressure gauge might be a good idea but as you stated, oils are much better now and are cars have not burned oil so the lower grade may be perfectly fine. I may give it a little more time before deciding since it is cooler now anyway and the lower grade seems to be working fine. Thanks again for the input.

 

[Merkava_4]

Quote:
my Volvos both recommend 5w30, 10w30 and 15w40


I don't suppose we couldn't slide 10W-40 in between the 10W-30 and 15W-40 then huh?

 

[coffee]

hehe, I am sure we could but I would need to check into that grade a little further.

 

[Curious Kid]

The stigma of large amounts of VII's to shear and leave deposits from formulations gone by, perhaps has left them to holdout such recommendation...I think many still do in the US.??? Aside from crossing paths with notation for a 0/5w-40 "synthetic" on the web, it also goes without notice in the manuals.

OEM's dated references???