I just recently got an oil change at a shop for my 1991 Volvo 240 with around 250k miles. I noticed after on the receipt they put in 5w30 blend oil. From what I understand this is for winter weather in colder conditions. I live in Southern California where the weather has been in the 50s-60s during the day. I’m not sure if there was a valid reason for using this oil when 10w30 is recommended. Any insight would be appreciated. I want to make sure this won’t be a detriment and am now a bit worried about this shop as they also triple charged me for the Mann filter they put on too.

 

Either are fine. What the shop did was fine.
​​​​​​Read this:


The viscosity of an oil is measured by its resistance to flow. There are two numbers that define viscosity meaning. The first number precedes the letter 'W' which stands for Winter. This measurement is related to how an oil flows when it is cold, such as at engine start-up. The second number is defined by how an oil flows at normal engine operating temperatures. The smaller the number, the better it will flow. A 5W-30 will flow easier than a 10W-30 at start-up temperatures and a 10W-30 will flow more easily than a 10W-40 at normal engine operating temperatures. Engine oil viscosity is important. Engine oils naturally thicken as they cool and thin as they are heated. Thin, low viscosity oils give better protection to engine parts at cold temperature. Thick, high viscosity oils are typically better at maintaining film strength to protect engines at high temperatures.
from

https://www.castrol.com/en_gb/united...ty-grades.html

 

for what it's worth i would always use valvoline 10w30 conventional and a mann filter. my indy started charging a ridiculous price for an oil change so
i went back to doing it myself. way less cost and honestly you could not find an easier engine to do an oil change on...and.. then you know it's done
right.

 

+1 on using OEM/Mann filters. I'd also recommend using a high mileage oil, which contains seal softeners. You can also find a synthetic high mileage or a synthetic blend. If you decide to try a synthetic, I'd suggest using a high mileage dino oil first since the synthetic can make hard seals weepy. To the OP, if you check the owners manual you will see Volvo recommends the oil weight by driving conditions - 5-30, 10-30 and even 15-40 are listed. Change intervals are 5K miles or 6 months...more frequent for hard driving conditions (ie city with lots of idle, mountains etc)

https://volvo.custhelp.com/app/manua...ual/om_id/1253