Switch to synthetic oil @ 175k?

[CA Cruisin]

Hi, I did a quick search but figgered I'd toss a quick query ~
I recently bought a 2004 and it has 175k miles. Runs great.
Still on regular oil.
Is there any advantage at this stage switching it to synthetic motor oil?
Any disadvantages other than cost?

I tend toward synth but won't if it's moot at this point in the engine's age.

Thanks for input.

 

[Julian Stead]

It’s only just run in, think of it as a BMW with 20k.

 

[Trunk Monkey]

I remember from the 80's forum a few folks reporting new leaks when switching to synthetic in a higher mile vehicle that had only run conventional. Most there would instead run a blend like Rotella.

 

[jahawk]

At 118,000 when I got mine I threw in synthetic. No idea what had been used previously, and no new leaks in the last 20,000 miles.

Jim

 

[Julian Stead]

I went from semi synthetic 10w 40 Toyota’s own brand to 0w 40 Mobil 1, no issues and maybe no benefits.

 

[suprarx7nut]

Switch to synthetic and never look back. Your intervals should be ~10k miles (~5k for the filter) so the cost is a wash. Get the the synthetic oil on sale and you can actually save money using good oil with long intervals. I just picked up 5 quarts of Castrol Syntec (now Edge) for under $30.

I use 0-40W or 0-30W Castrol Edge, Mobil1 or Pennzoil Platinum, whichever's on sale. Filters I use only Toyota, Pureone, Mobil1, K&N or maybe Wix Gold/Bosch if that's all that's available. Most cheaper filters are fine, but I think the extra few dollars for the top tier is money very well spent for the sole filtration device for your engine.

If synthetic oil reveals new leaks I'm a believer those leaks were on the verge of showing up anyways. The leaks were simply being held shut by dirt and debris. Once the synthetic oil cleans it out with its generally superior detergents, boom, there's the leak. It was always there, the inferior oil was just allowing those tiny bits of debris to hold it closed.

The one exception would be the high mileage blends which can have additives that cause some seals to swell to maintain a seal for a tiny bit longer. I'm still not sure that benefit outweighs the benefits of a good fully synthetic oil.

 

[Julian Stead]

Toyota used to give me free oil when I purchased a oil filter and air filter. No brand of oil beats free oil. Only when this offer ended I switched to fully synthetic. They still give free brake fluid with a set of brake pads.

 

[Spike555]

Make the switch and don't look back, especially if you live where it gets below zero or above 100.

 

[BullElk]

Just keep using the Walmart Super Tech like I do in all mine....but my personality is to not overthink too much. It's worked out well.

 

[DirtDawg]

I’m running amsoil synthetic on 15k intervals. I used to be a 5k interval guy, but after using a ton of different synthetics and with results from various blackstone reports, decided to switch to 10, then 15k. Blackstone says I’d be good to run it for 20k.

 

[abuck99]

Started with M1 full syn (extended performance) when I bought my rig at 165k miles. No leaks or issues. SoCal traffic, summer heat, highway miles syn would be a good choice.

 

[guardcompany]

I switched to Mobile 1 full syn HM @ 140k and 10k later zero issues.

 

[seanz0rz]

I am not sure what my PO put in (probably cooking oil from what I have discovered after buying the vehicle...) but I have been running Mobil 1 Synthetic 5W30 for about 20k miles now, no issues or leaks. I have run the same in my 4runner for 70k-ish miles and again, no issues.

 

[Dox]

Switched at 220k to Royal Purple and gained a mpg, no issues 20k miles later.

 

[Cargo1234]

Sam's Club had Mobil1 on sale a few weeks back case of 6 for $22.78.
Seemed like a no brainer to go full Synth.

 

[Rolocado]

Switch to synthetic and never look back. Your intervals should be ~10k miles (~5k for the filter) so the cost is a wash. Get the the synthetic oil on sale and you can actually save money using good oil with long intervals. I just picked up 5 quarts of Castrol Syntec (now Edge) for under $30.

I use 0-40W or 0-30W Castrol Edge, Mobil1 or Pennzoil Platinum, whichever's on sale. Filters I use only Toyota, Pureone, Mobil1, K&N or maybe Wix Gold/Bosch if that's all that's available. Most cheaper filters are fine, but I think the extra few dollars for the top tier is money very well spent for the sole filtration device for your engine.

If synthetic oil reveals new leaks I'm a believer those leaks were on the verge of showing up anyways. The leaks were simply being held shut by dirt and debris. Once the synthetic oil cleans it out with its generally superior detergents, boom, there's the leak. It was always there, the inferior oil was just allowing those tiny bits of debris to hold it closed.

The one exception would be the high mileage blends which can have additives that cause some seals to swell to maintain a seal for a tiny bit longer. I'm still not sure that benefit outweighs the benefits of a good fully synthetic oil.

Whoaaa... new information just dawned on me... I have a subaru forester that has M1 Synthetic good for 15k miles and just a normal subaru filter good for probably 5k miles... I can just switch the filter without doing a whole oil change can't I..?

 

[suprarx7nut]

Whoaaa... new information just dawned on me... I have a subaru forester that has M1 Synthetic good for 15k miles and just a normal subaru filter good for probably 5k miles... I can just switch the filter without doing a whole oil change can't I..?

That's been my method, yes. Filter at around 5k (I've forgotten a few times and never sweat it). Some filters claim effectiveness to 10k and beyond, so your filters may be fine to 15k as well.

Modern lubricant technology is astounding. The filters, equally so. Any information that applied 10-15 years ago to conventional oil and filter media is essentially null and void compared to modern synthetic oil and filtration. Enjoy the 15k intervals!

 

[Spike555]

I’m running amsoil synthetic on 15k intervals. I used to be a 5k interval guy, but after using a ton of different synthetics and with results from various blackstone reports, decided to switch to 10, then 15k. Blackstone says I’d be good to run it for 20k.

I'm doing my first ever 10k on Rotella T6 (been using that for 10yrs) and am going to do a oil sample to see what it says.
Purolator PureOne oil filter good for 10k.