Mixing Conventional And Synthetic Atf (2024)

Hi All,

I'm thinking of moving to synthetic for my 2003 Yukon XL, with about 57k on it.

I don't have the parts and I don't think I'll be able to do the "manual flush" like this, and I'm wondering if it would be a problem to just put in Amsoil ATF, or some other synthetic ATF. Drop the pan, drain the fluid, change the filter, then refill with Amsoil. I understand this is going to leave about 50% of the old fluid in the vehicle, so I'll now have 50% convention and 50% synthetic.

I'll likely drop the pan and drain again in short order, perhaps 6 months or 10,000 miles, whichever comes first, and then again 6 months later or 10,000 more miles. I figure that way I'll get most of the conventional ATF out and have it replaced with synthetic.

I've searched and read a ton on transmission fluid changes, and it seems that the general consensus on mixing synthetic and conventional ATF is that it's ok, it's just that you won't get the full benefit of synthetic ATF as long as you've got it mixed with conventional. After three changes, I should be to 87.5% synthetic, if dropping the pan will drain out 50% of the fluid.

I thought I'd ask here, one last time, to see if the conclusion I've drawn (mixing is ok) from my own reading is in error. Let me know your thoughts. Thanks!

-Josh

Mixing Conventional And Synthetic Atf (2024)

FAQs

Mixing Conventional And Synthetic Atf? ›

Yes, you can mix a conventional and synthetic transmission fluid of the same specification. Basically, the full benefits of the synthetic fluid won't be realized especially if the vehicle is operated in severe service conditions.

Can I mix synthetic transmission fluid with conventional transmission fluid? ›

Is it OK to mix synthetic ATF with a conventional and/or synthetic blend ATF? Yes. Synthetic ATF and conventional fluids are 100 percent compatible with each other.

Can you mix two different types of transmission fluid? ›

Using the wrong type of transmission fluid for high-tech vehicles can result in irreversible damage. One should never mix regular manual or automatic transmission fluid with CVT fluid or vice versa. While an advanced car can run with the wrong transmission fluid, it will end in damage.

Can I mix old and new transmission fluid? ›

Do not mix brands. Also only let out what the drain plug allows unless you are changing regularly 30–50,000 miles. If it's been in their a while especially American cars leave it be. You can cause slippage.

Can you mix ATF and manual transmission fluid? ›

ATF is for automatic gearboxes and presumably your gear oil shows a viscosity like 80/90, 80 etc so is for a manual gearbox. They are for different things so may damage your automatic gearbox if mixed and used in that.

What happens if you mix conventional and synthetic? ›

Can You Mix Conventional Oil With Synthetic? The short answer is yes. There is no danger or risk of combustion, and mixing the two types of oil won't harm your engine. However, it's important to note that if you do mix the two, the conventional oil can keep the synthetic from performing to its fullest potential.

Is synthetic transmission fluid better than regular transmission fluid? ›

Unlike traditional mineral-based fluids, synthetic fluid has superior lubrication properties that offer better protection to the gears, bearings, and other transmission system components. Mineral-based fluids deteriorate over time, losing their lubrication properties, especially under high temperatures and heavy loads.

Is it OK to mix different brands of ATF? ›

Yes as long as they are the same type there should not be a problem. By type I mean the specific type recommended by the manufacturer such as dexron for GM vehicles and AFT+4 for Dodge vehicles. Synthetic and non Synthetic can be used together such as if you need to top off the fluid level.

Can you mix Dexron 3 and Dexron 6? ›

DEXRON-VI is also compatible with any former version of DEXRON for use in automatic transmissions. TIP: Simply topping off the fluid is adequate, but a full drain and replacement is preferred, to obtain the full benefit. Save this answer.

What happens if you mix Type F and Dexron? ›

Yes it's ok, a 50/50 mix of Type F and Dexron is often recommended for higher HP applications, the best of both worlds-firmer shifts with Type F but with the added lubricity of Dexron.

Why do people say never change transmission fluid? ›

That bad fluid may have a “sticky” quality to it or metal flecks that act to aid friction, and if it's changed, the new fluid might cause the transmission to start slipping.

Can I just add transmission fluid instead of changing it? ›

You can always top off your trans fluid, and you should top it off anytime it is low. For maintenance, there are 2 different types of fluid changes. One is a 'Flush', the other is a 'Change'.

Can you mix dexron 3 with ATF? ›

As to ATF, no problem mixing Dexron and Type F, one can actually fine tune shift harshness as Type F is in fact "grippier".

Can I mix ATF and ATF 4? ›

Do not mix ATF+4® with non-licensed automatic transmission fluid (ATF). To ensure you have removed most or all of the existing ATF in your transmission, it is recommended that you perform a total of three (3) fluid changes using ATF+4®.

What happens if you mix automatic transmission fluid with power steering fluid? ›

You should be fine. ATF and PS fluid are basically the same hydraulic oil, despite the difference in color, which is probably to help identify the source of a leak.

Can you use synthetic transmission fluid on older cars? ›

Multi-Vehicle Synthetic Transmission Fluid:

Recommended for older (mostly pre-2006) vehicles that require a higher-viscosity fluid.

Can you use automatic transmission fluid in a standard transmission? ›

Will automatic transmission fluid work in a manual transmission? Yes – provided the original equipment manufacturer recommends it. It's important to check your owner's manual to make sure before dumping ATF in your manual transmission. In fact, some manuals may call for a gear lube or even a motor oil in older units.

Can you mix dexron and Type F transmission fluid? ›

Yes it's ok, a 50/50 mix of Type F and Dexron is often recommended for higher HP applications, the best of both worlds-firmer shifts with Type F but with the added lubricity of Dexron.

What's the difference between ATF and dexron transmission fluid? ›

Dextron is a General Motors approved trans fluid (there are a few versions), and ATF is a generic name for trans fluid. Dextron can and is used in many other makes of vehicles (not just GM), and you need to make certain you are putting the correct fluid in whatever car you own so research whatever applies.

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